@classmethod
def restore_padding(cls, receipt):
    """Restore padding based on receipt size.

        :param receipt: receipt to restore padding on
        :type receipt: six.text_type
        :returns: receipt with correct padding

        """
    mod_returned = len(receipt) % 4
    if mod_returned:
        missing_padding = 4 - mod_returned
        receipt += '=' * missing_padding
    return receipt
