code: def bytes_replace(byte_str, start_idx, stop_idx, replacement):
      
      return byte_str[:start_idx] + replacement + byte_str[stop_idx:]
docs: Replaces given portion of the byte string with the replacement, returns new array
      :param byte_str:
      :param start_idx:
      :param stop_idx:
      :param replacement:
      :return: