input: from typing import List
  
  def binary_xor(str1: str, str2: str) -> str:
      """ Takes two binary strings str1 and str2 as inputs.
      Apply XOR operation on these inputs and return the result as a binary string.
      >>> binary_xor('010', '110')
      '100'
      """
output:     
      # Calculate the XOR of two binary strings
      result = []
      for b1, b2 in zip(str1, str2):
          result.append('1' if b1 != b2 else '0')
      return ''.join(result)
  