code: def fill_padding(padded_string):
      # type: (bytes) -> bytes
      
      length = len(padded_string)
      reminder = len(padded_string) % 4
      if reminder:
          return padded_string.ljust(length + 4 - reminder, b'.')
      return padded_string
docs: Fill up missing padding in a string.
  
      This function makes sure that the string has length which is multiplication of 4,
      and if not, fills the missing places with dots.
  
      :param str padded_string: string to be decoded that might miss padding dots.
      :return: properly padded string
      :rtype: str