diff --git a/lib/arrayBlock.ts b/lib/arrayBlock.ts
index ccddeab..2ba209c 100644
--- a/lib/arrayBlock.ts
+++ b/lib/arrayBlock.ts
@@ -1,10 +1,9 @@
 import CompositeBlock from './compositeBlock';
 import { createError, ERROR_ID } from './error';
-import type { DescriptError } from './error';
 import type {
     BlockResultOut,
     First,
-    InferResultFromBlock,
+    InferResultOrError,
     InferParamsInFromBlock,
     Tail,
     DescriptBlockOptions,
@@ -17,8 +16,8 @@ import type DepsDomain from './depsDomain';
 
 export type GetArrayBlockResult<T extends ReadonlyArray<unknown>> = {
     0: never;
-    1: [ InferResultFromBlock<First<T>> | DescriptError ];
-    2: [ InferResultFromBlock<First<T>> | DescriptError, ...GetArrayBlockResult<Tail<T>> ];
+    1: [ InferResultOrError<First<T>> ];
+    2: [ InferResultOrError<First<T>>, ...GetArrayBlockResult<Tail<T>> ];
 }[ T extends [] ? 0 : T extends ((readonly [ any ]) | [ any ]) ? 1 : 2 ];
 
 export type GetArrayBlockParamsUnion<T extends ReadonlyArray<unknown>> = {
@@ -72,20 +71,42 @@ class ArrayBlock<
     > {
 
     extend<
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        ExtendedResultOut extends
-        BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): ArrayBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: ArrayBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): ArrayBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options }: {
-        options: DescriptBlockOptions<
-            Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams
-        >;
-    }) {
+    >(args: {
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): ArrayBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options }: { options?: any }): any {
         return new ArrayBlock({
             block: this.extendBlock(this.block),
             options: this.extendOptions(this.options, options) as typeof options,
diff --git a/lib/block.ts b/lib/block.ts
index 90982a8..4d8390f 100644
--- a/lib/block.ts
+++ b/lib/block.ts
@@ -66,27 +66,40 @@ abstract class BaseBlock<
     }
 
     abstract extend<
-
-        // ExtendedResultOut extends
-        // BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
-        // ExtendedCustomBlock = CustomBlock,
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ block, options }: {
+    >(args: {
         block?: CustomBlock;
-        options?: DescriptBlockOptions<
-            Context,
-            ParamsOut & ExtendedParamsOut,
-            ExtendedBlockResult,
-            ExtendedBeforeResultOut,
-            ExtendedAfterResultOut,
-            ExtendedErrorResultOut,
-            ExtendedParams
-        >;
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): unknown;
+    abstract extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: BaseBlock<Context, CustomBlock, ParamsOut, ResultOut, IntermediateResult, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            block?: CustomBlock;
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): unknown;
+    abstract extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        block?: CustomBlock;
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
     }): unknown;
 
     protected initBlock(block: CustomBlock) {
diff --git a/lib/firstBlock.ts b/lib/firstBlock.ts
index 24e2db8..cfb693c 100644
--- a/lib/firstBlock.ts
+++ b/lib/firstBlock.ts
@@ -5,7 +5,7 @@ import type BaseBlock from './block';
 import type {
     BlockResultOut,
     First,
-    InferResultFromBlock,
+    InferResultOrError,
     InferParamsInFromBlock,
     Tail,
     DescriptBlockOptions,
@@ -32,21 +32,14 @@ export type GetFirstBlockParams<
     PU = GetFirstBlockParamsUnion<PA>,
 > = PU;
 
-type GetFirstBlockResultMap<T extends ReadonlyArray<unknown>> = {
-    [ P in keyof T ]: InferResultFromBlock<T[ P ]>;
-};
-
 type GetFirstBlockResultUnion<T extends ReadonlyArray<unknown>> = {
     0: never;
-    1: First<T> | DescriptError;
-    2: First<T> | DescriptError | GetFirstBlockResultUnion<Tail<T>>;
+    1: InferResultOrError<First<T>>;
+    2: InferResultOrError<First<T>> | GetFirstBlockResultUnion<Tail<T>>;
 }[ T extends [] ? 0 : T extends ((readonly [ any ]) | [ any ]) ? 1 : 2 ];
 
-export type GetFirstBlockResult<
-    T extends ReadonlyArray<unknown>,
-    PA extends ReadonlyArray<unknown> = GetFirstBlockResultMap<T>,
-    PU = GetFirstBlockResultUnion<PA>,
-> = PU;
+export type GetFirstBlockResult<T extends ReadonlyArray<unknown>> =
+    GetFirstBlockResultUnion<T>;
 
 export type FirstBlockDefinition<T> = {
     [ P in keyof T ]: T[ P ] extends BaseBlock<
@@ -83,21 +76,42 @@ class FirstBlock<
     > {
 
     extend<
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        ExtendedResultOut extends
-        BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
-        // ExtendedCustomBlock extends FirstBlockDefinition<Block>,
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): FirstBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: FirstBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): FirstBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options }: {
-        options: DescriptBlockOptions<
-            Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams
-        >;
-    }) {
+    >(args: {
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): FirstBlock<Context, Block, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options }: { options?: any }): any {
         return new FirstBlock({
             block: this.extendBlock(this.block),
             options: this.extendOptions(this.options, options) as typeof options,
diff --git a/lib/functionBlock.ts b/lib/functionBlock.ts
index 29234b7..c53d75d 100644
--- a/lib/functionBlock.ts
+++ b/lib/functionBlock.ts
@@ -97,28 +97,39 @@ class FunctionBlock<
     extend<
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        // ExtendedCustomBlock = DescriptHttpBlockDescription<ExtendedParamsOut, Context, HttpResult>,
-
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options }: {
-        options: DescriptBlockOptions<
-            Context,
-            ExtendedParamsOut,
-            ExtendedBlockResult,
-            ExtendedBeforeResultOut,
-            ExtendedAfterResultOut,
-            ExtendedErrorResultOut,
-            ExtendedParams
-        >;
-    }) {
+    >(args: {
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): FunctionBlock<Context, ExtendedParamsOut, ExtendedBlockResult, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: FunctionBlock<Context, ParamsOut, BlockResult, ResultOut, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): FunctionBlock<Context, ExtendedParamsOut, ExtendedBlockResult, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): FunctionBlock<Context, ExtendedParamsOut, ExtendedBlockResult, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options }: { options?: any }): any {
         return new FunctionBlock({
             block: this.extendBlock(this.block) as typeof this.block,
-            // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-            // @ts-expect-error
             options: this.extendOptions(this.options, options) as typeof options,
         });
     }
diff --git a/lib/httpBlock.ts b/lib/httpBlock.ts
index 27a3007..c0958fd 100644
--- a/lib/httpBlock.ts
+++ b/lib/httpBlock.ts
@@ -205,30 +205,43 @@ class HttpBlock<
         ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
-
-        // ExtendedCustomBlock = DescriptHttpBlockDescription<ExtendedParamsOut, Context, HttpResult>,
-
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options, block }: {
+    >(args: {
         block?: DescriptHttpBlockDescription<ParamsOut & ExtendedParamsOut, Context, HttpResult>;
-        options?: DescriptBlockOptions<
-            Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams
-        >;
-    }) {
-        const x = new HttpBlock<
-            Context,
-            ExtendedParamsOut,
-            HttpResult,
-            ExtendedResultOut,
-            ExtendedBlockResult,
-            ExtendedBeforeResultOut,
-            ExtendedAfterResultOut,
-            ExtendedErrorResultOut,
-            ExtendedParams
-        >({
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): HttpBlock<Context, ExtendedParamsOut, HttpResult, ExtendedResultOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: HttpBlock<Context, ParamsOut, HttpResult, ResultOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            block?: DescriptHttpBlockDescription<ParamsOut & ExtendedParamsOut, Context, HttpResult>;
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): HttpBlock<Context, ExtendedParamsOut, HttpResult, ExtendedResultOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        block?: DescriptHttpBlockDescription<ParamsOut & ExtendedParamsOut, Context, HttpResult>;
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): HttpBlock<Context, ExtendedParamsOut, HttpResult, ExtendedResultOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options, block }: { block?: any; options?: any }): any {
+        const x = new HttpBlock({
             block: this.extendBlock(block),
             options: this.extendOptions(this.options, options),
         });
diff --git a/lib/index.ts b/lib/index.ts
index a1c745d..19107d6 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -24,6 +24,8 @@ import type {
     DescriptBlockOptions,
     DescriptHttpBlockHeaders,
     InferResultFromBlock,
+    DeepInferResultFromBlock,
+    DeepResolveResult,
     InferParamsInFromBlock,
     InferBlock,
     InferHttpBlock,
@@ -32,116 +34,205 @@ import type {
 } from './types';
 import type BaseBlock from './block';
 import type { DescriptHttpBlockDescription, DescriptHttpBlockQuery, DescriptHttpBlockQueryValue } from './httpBlock';
-import type { GetObjectBlockParams, GetObjectBlockResult, ObjectBlockDefinition } from './objectBlock';
+import type { GetObjectBlockParams, GetObjectBlockResult } from './objectBlock';
 import type { GetArrayBlockParams, GetArrayBlockResult, ArrayBlockDefinition } from './arrayBlock';
 import type { GetFirstBlockParams, GetFirstBlockResult, FirstBlockDefinition } from './firstBlock';
 import type { GetPipeBlockParams, GetPipeBlockResult, PipeBlockDefinition } from './pipeBlock';
 import PipeBlock from './pipeBlock';
 
-const func = function<
-    Context,
-    ParamsOut,
-    BlockResult,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = ParamsOut,
->({ block, options }: {
-    block: FunctionBlockDefinition<Context, ParamsOut, BlockResult>;
-    options?: DescriptBlockOptions<
-        Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params
-    >;
-} & ([ ExtractBadNestedParams<BlockResult, ParamsOut> ] extends [ never ] ? unknown : ExtractBadNestedParams<BlockResult, ParamsOut>)) {
-    return new FunctionBlock<
-        Context, ParamsOut, BlockResult, ResultOut, BeforeResultOut, AfterResultOut, ErrorResultOut, Params
-    >({ block, options });
+const func: {
+    <
+        Context,
+        ParamsOut,
+        BlockResult,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = ParamsOut,
+    >(args: {
+        block: FunctionBlockDefinition<Context, ParamsOut, BlockResult>;
+        options: DescriptBlockOptions<Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    } & ([ ExtractBadNestedParams<BlockResult, ParamsOut> ] extends [ never ] ? unknown : ExtractBadNestedParams<BlockResult, ParamsOut>)): FunctionBlock<Context, ParamsOut, BlockResult, ResultOut, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        ParamsOut,
+        BlockResult,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = ParamsOut,
+    >(args: {
+        block: FunctionBlockDefinition<Context, ParamsOut, BlockResult>;
+        options?: DescriptBlockOptions<Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    } & ([ ExtractBadNestedParams<BlockResult, ParamsOut> ] extends [ never ] ? unknown : ExtractBadNestedParams<BlockResult, ParamsOut>)): FunctionBlock<Context, ParamsOut, BlockResult, ResultOut, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any): any {
+    return new FunctionBlock({ block, options });
 };
-const array = function<
-    Context,
-    Block extends ReadonlyArray<unknown>,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    ParamsOut = GetArrayBlockParams<Block>,
-    BlockResult = GetArrayBlockResult<Block>,
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = GetArrayBlockParams<Block>,
->({ block, options }: {
-    block: ArrayBlockDefinition<Block>;
-    options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
-}) {
-    return new ArrayBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>({ block, options });
+const array: {
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetArrayBlockParams<Block>,
+        BlockResult = GetArrayBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetArrayBlockParams<Block>,
+    >(args: {
+        block: ArrayBlockDefinition<Block>;
+        options: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    }): ArrayBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetArrayBlockParams<Block>,
+        BlockResult = GetArrayBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetArrayBlockParams<Block>,
+    >(args: {
+        block: ArrayBlockDefinition<Block>;
+        options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    }): ArrayBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any): any {
+    return new ArrayBlock({ block, options });
 };
-const object = function<
-    Context,
-    Blocks extends Record<string, any>,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    ParamsOut = GetObjectBlockParams<Blocks>,
-    BlockResult = GetObjectBlockResult<Blocks>,
-
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = GetObjectBlockParams<Blocks>,
->({ block, options }: {
-    block?: ObjectBlockDefinition<Blocks>;
-    options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
-} = {}) {
-    return new ObjectBlock<Context, Blocks, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>({ block, options });
+const object: {
+    <
+        Context,
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        Blocks extends Record<string, any>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetObjectBlockParams<Blocks>,
+        BlockResult = GetObjectBlockResult<Blocks>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetObjectBlockParams<Blocks>,
+    >(args: {
+        block?: Blocks;
+        options: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    }): ObjectBlock<Context, Blocks, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        Blocks extends Record<string, any>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetObjectBlockParams<Blocks>,
+        BlockResult = GetObjectBlockResult<Blocks>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetObjectBlockParams<Blocks>,
+    >(args?: {
+        block?: Blocks;
+        options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    }): ObjectBlock<Context, Blocks, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any = {}): any {
+    return new ObjectBlock({ block, options });
 };
-const http = function<
-    Context,
-    ParamsOut,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    IntermediateResult,
-    BlockResult extends DescriptHttpBlockResult<IntermediateResult>,
-
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = ParamsOut,
->({ block, options }: {
-    block?: DescriptHttpBlockDescription<ParamsOut, Context, IntermediateResult>;
-    options?: DescriptBlockOptions<Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
-}) {
-    return new HttpBlock<
-        Context, ParamsOut, IntermediateResult, ResultOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params
-    >({ block, options });
+const http: {
+    <
+        Context,
+        ParamsOut,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        IntermediateResult,
+        BlockResult extends DescriptHttpBlockResult<IntermediateResult>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = ParamsOut,
+    >(args: {
+        block?: DescriptHttpBlockDescription<ParamsOut, Context, IntermediateResult>;
+        options: DescriptBlockOptions<Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    }): HttpBlock<Context, ParamsOut, IntermediateResult, ResultOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        ParamsOut,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        IntermediateResult,
+        BlockResult extends DescriptHttpBlockResult<IntermediateResult>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = ParamsOut,
+    >(args: {
+        block?: DescriptHttpBlockDescription<ParamsOut, Context, IntermediateResult>;
+        options?: DescriptBlockOptions<Context, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    }): HttpBlock<Context, ParamsOut, IntermediateResult, ResultOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any): any {
+    return new HttpBlock({ block, options });
 };
 
-const first = function<
-    Context,
-    Block extends ReadonlyArray<unknown>,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    ParamsOut = GetFirstBlockParams<Block>,
-    BlockResult = GetFirstBlockResult<Block>,
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = GetFirstBlockParams<Block>,
->({ block, options }: {
-    block: FirstBlockDefinition<Block>;
-    options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
-}) {
-    return new FirstBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>({ block, options });
+const first: {
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetFirstBlockParams<Block>,
+        BlockResult = GetFirstBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetFirstBlockParams<Block>,
+    >(args: {
+        block: FirstBlockDefinition<Block>;
+        options: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    }): FirstBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetFirstBlockParams<Block>,
+        BlockResult = GetFirstBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetFirstBlockParams<Block>,
+    >(args: {
+        block: FirstBlockDefinition<Block>;
+        options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    }): FirstBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any): any {
+    return new FirstBlock({ block, options });
 };
 
-const pipe = function<
-    Context,
-    Block extends ReadonlyArray<unknown>,
-    ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
-    ParamsOut = GetPipeBlockParams<Block>,
-    BlockResult = GetPipeBlockResult<Block>,
-    BeforeResultOut = unknown,
-    AfterResultOut = unknown,
-    ErrorResultOut = unknown,
-    Params = GetPipeBlockParams<Block>,
->({ block, options }: {
-    block: PipeBlockDefinition<Block>;
-    options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
-}) {
-    return new PipeBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>({ block, options });
+const pipe: {
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetPipeBlockParams<Block>,
+        BlockResult = GetPipeBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetPipeBlockParams<Block>,
+    >(args: {
+        block: PipeBlockDefinition<Block>;
+        options: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { required: true };
+    }): PipeBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true };
+    <
+        Context,
+        Block extends ReadonlyArray<unknown>,
+        ResultOut extends BlockResultOut<BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut>,
+        ParamsOut = GetPipeBlockParams<Block>,
+        BlockResult = GetPipeBlockResult<Block>,
+        BeforeResultOut = unknown,
+        AfterResultOut = unknown,
+        ErrorResultOut = unknown,
+        Params = GetPipeBlockParams<Block>,
+    >(args: {
+        block: PipeBlockDefinition<Block>;
+        options?: DescriptBlockOptions<Context, NoInfer<ParamsOut>, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+    }): PipeBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params>;
+} = function({ block, options }: any): any {
+    return new PipeBlock({ block, options });
 };
 
 const isBlock = function(block: any) {
@@ -211,6 +302,8 @@ export {
     GenerateId,
     DescriptBlockId,
     InferResultFromBlock,
+    DeepInferResultFromBlock,
+    DeepResolveResult,
     InferParamsInFromBlock,
     InferBlock,
     DescriptBlockDeps,
diff --git a/lib/objectBlock.ts b/lib/objectBlock.ts
index 5e7500e..f73135e 100644
--- a/lib/objectBlock.ts
+++ b/lib/objectBlock.ts
@@ -18,7 +18,9 @@ export type InferResultFromObjectBlocks<Block> = Block extends BaseBlock<
     Block;
 
 export type GetObjectBlockResult<T extends Record<string, any>> = {
-    [ P in keyof T ]: InferResultFromBlock<T[P]> | DescriptError
+    [ P in keyof T ]: T[P] extends { readonly __isRequired: true }
+        ? InferResultFromBlock<T[P]>
+        : InferResultFromBlock<T[P]> | DescriptError
 };
 
 export type GetObjectBlockParams<
@@ -106,21 +108,42 @@ class ObjectBlock<
     }
 
     extend<
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        ExtendedResultOut extends
-        BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
-        // ExtendedCustomBlock extends ObjectBlockDefinition<Blocks>,
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): ObjectBlock<Context, Blocks, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: ObjectBlock<Context, Blocks, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): ObjectBlock<Context, Blocks, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedResultOut extends BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options }: {
-        options: DescriptBlockOptions<
-            Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams
-        >;
-    }) {
+    >(args: {
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): ObjectBlock<Context, Blocks, ExtendedResultOut, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options }: { options?: any }): any {
         return new ObjectBlock({
             block: this.extendBlock(this.block),
             options: this.extendOptions(this.options, options) as typeof options,
diff --git a/lib/pipeBlock.ts b/lib/pipeBlock.ts
index e9a607f..cfca164 100644
--- a/lib/pipeBlock.ts
+++ b/lib/pipeBlock.ts
@@ -1,12 +1,12 @@
 import CompositeBlock from './compositeBlock';
 import { ERROR_ID, createError } from './error';
-import type { DescriptError } from './error';
 import type BaseBlock from './block';
 import type {
     BlockResultOut,
     First,
-    InferResultFromBlock,
+    InferResultOrError,
     InferParamsInFromBlock,
+    Last,
     Tail,
     DescriptBlockOptions,
 } from './types';
@@ -32,21 +32,8 @@ export type GetPipeBlockParams<
     PU = GetPipeBlockParamsUnion<PA>,
 > = PU;
 
-type GetPipeBlockResultUnion<T extends ReadonlyArray<unknown>> = {
-    0: never;
-    1: First<T> | DescriptError;
-    2: First<T> | DescriptError | GetPipeBlockResultUnion<Tail<T>>;
-}[ T extends [] ? 0 : T extends ((readonly [ any ]) | [ any ]) ? 1 : 2 ];
-
-type GetPipeBlockResultMap<T extends ReadonlyArray<unknown>> = {
-    [ P in keyof T ]: InferResultFromBlock<T[ P ]>;
-};
-
-export type GetPipeBlockResult<
-    T extends ReadonlyArray<unknown>,
-    PA extends ReadonlyArray<unknown> = GetPipeBlockResultMap<T>,
-    PU = GetPipeBlockResultUnion<PA>,
-> = PU;
+export type GetPipeBlockResult<T extends ReadonlyArray<unknown>> =
+    InferResultOrError<Last<T>>;
 
 export type PipeBlockDefinition<T> = {
     [ P in keyof T ]: T[ P ] extends BaseBlock<
@@ -83,21 +70,39 @@ class PipeBlock<
     > {
 
     extend<
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        // ExtendedResultOut extends
-        // BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>,
-        // ExtendedCustomBlock extends PipeBlockDefinition<Block>,
         ExtendedParamsOut extends Params = Params,
         ExtendedParams = Params,
         ExtendedBlockResult = ResultOut,
         ExtendedBeforeResultOut = unknown,
         ExtendedAfterResultOut = unknown,
         ExtendedErrorResultOut = unknown,
-    >({ options }: {
-        options: DescriptBlockOptions<
-            Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams
-        >;
-    }) {
+    >(args: {
+        options: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required: true };
+    }): PipeBlock<Context, Block, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(
+        this: PipeBlock<Context, Block, ResultOut, ParamsOut, BlockResult, BeforeResultOut, AfterResultOut, ErrorResultOut, Params> & { readonly __isRequired: true },
+        args: {
+            options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { required?: true };
+        }
+    ): PipeBlock<Context, Block, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams> & { readonly __isRequired: true };
+    extend<
+        ExtendedParamsOut extends Params = Params,
+        ExtendedParams = Params,
+        ExtendedBlockResult = ResultOut,
+        ExtendedBeforeResultOut = unknown,
+        ExtendedAfterResultOut = unknown,
+        ExtendedErrorResultOut = unknown,
+    >(args: {
+        options?: DescriptBlockOptions<Context, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    }): PipeBlock<Context, Block, BlockResultOut<ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut>, ExtendedParamsOut, ExtendedBlockResult, ExtendedBeforeResultOut, ExtendedAfterResultOut, ExtendedErrorResultOut, ExtendedParams>;
+    extend({ options }: { options?: any }): any {
         return new PipeBlock({
             block: this.extendBlock(this.block),
             options: this.extendOptions(this.options, options) as typeof options,
diff --git a/lib/types.ts b/lib/types.ts
index 4700502..7c92f47 100644
--- a/lib/types.ts
+++ b/lib/types.ts
@@ -104,6 +104,11 @@ export type InferResultOrResultOnce<Result> = Result extends BaseBlock<
     infer BlockResult, infer BeforeResultOut, infer AfterResultOut, infer ErrorResultOut, infer Params
 > ? ResultOut : Result;
 
+export type InferResultOrError<T> =
+    T extends { readonly __isRequired: true }
+        ? InferResultFromBlock<T>
+        : InferResultFromBlock<T> | DescriptError;
+
 export type InferResultFromBlock<Type> = Type extends BaseBlock<
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
     infer Context, infer CustomBlock, infer ParamsOut, infer ResultOut, infer IntermediateResult,
@@ -111,6 +116,18 @@ export type InferResultFromBlock<Type> = Type extends BaseBlock<
     infer BlockResult, infer BeforeResultOut, infer AfterResultOut, infer ErrorResultOut, infer Params
 > ? InferResultOrResult<ResultOut> : never;
 
+export type DeepResolveResult<T> =
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    T extends BaseBlock<any, any, any, infer ResultOut, any, any, any, any, any, any>
+        ? DeepResolveResult<InferResultOrResult<ResultOut>>
+        : T extends DescriptError
+            ? DescriptError
+            : T extends Record<string, unknown>
+                ? { [K in keyof T]: DeepResolveResult<T[K]> }
+                : T;
+
+export type DeepInferResultFromBlock<T> = DeepResolveResult<InferResultFromBlock<T>>;
+
 export type InferParamsInFromBlock<Type> = Type extends BaseBlock<
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
     infer Context, infer CustomBlock, infer ParamsOut, infer ResultOut, infer IntermediateResult,
@@ -161,6 +178,10 @@ export type Tail<T> =
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
     T extends readonly [ infer First, ...infer Rest ] | [ infer First, ...infer Rest ] ? Rest : never;
 
+export type Last<T> =
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+    T extends readonly [ ...infer _Rest, infer L ] | [ ...infer _Rest, infer L ] ? L : never;
+
 export type Equal<A, B> = A extends B ? (B extends A ? A : never) : never;
 
 export type DepsIds = Array<DescriptBlockId<any> | UntypedId>;