addBinaryUPDATE

class Solution:
    def addBinary(self, a, b):
        maximo_L = max(len(a), len(b))
        a = a.zfill(maximo_L)
        b = b.zfill(maximo_L)
        
        result = ''
        carry = 0
        # so maximo_L - 1 is just starting from back
        # decrease by 1 from the back
        # I guess stop is -1 but it stops when for loop fails??
        # not clear on last one
        # range(start, stop, step)
        for i in range(maximo_L-1, -1, -1):
            # int cuz its a string
            mySum = int(a[i]) + int(b[i]) + carry
            carry = mySum // 2
            result = str(mySum % 2) + result
        
        if carry:
            result = '1' + result
            
        return result

myVar = Solution()
myVar.addBinary("1010", "1011")