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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fill_padding(padded_string):
 # type: (bytes) -> bytes """ 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 """

    length = len(padded_string)
    reminder = len(padded_string) % 4
    if reminder:
        return padded_string.ljust(length + 4 - reminder, b'.')
    return padded_string