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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 dump(cls, data, encoding="ascii"):
 """ Convert str to appropriate format for "UserComment". :param data: Like u"foobar" :param str encoding: "ascii", "jis", or "unicode" :return: b"ASCII\x00\x00\x00foobar" :rtype: bytes :raises: ValueError if the encoding is unsupported. """

        if encoding not in cls.ENCODINGS:
            raise ValueError('encoding {!r} must be one of {!r}'.format(encoding, cls.ENCODINGS))
        prefix = {cls.ASCII: cls._ASCII_PREFIX, cls.JIS: cls._JIS_PREFIX, cls.UNICODE: cls._UNICODE_PREFIX}[encoding]
        internal_encoding = {cls.UNICODE: cls._UNICODE, cls.JIS: cls._JIS}.get(encoding, encoding)
        return prefix + data.encode(internal_encoding, errors='replace')