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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 set_charset(self, charset):
 """Set the charset of the payload to a given character set. charset can be a Charset instance, a string naming a character set, or None. If it is a string it will be converted to a Charset instance. If charset is None, the charset parameter will be removed from the Content-Type field. Anything else will generate a TypeError. The message will be assumed to be of type text/* encoded with charset.input_charset. It will be converted to charset.output_charset and encoded properly, if needed, when generating the plain text representation of the message. MIME headers (MIME-Version, Content-Type, Content-Transfer-Encoding) will be added as needed. """

        if charset is None:
            self.del_param('charset')
            self._charset = None
            return
        if not isinstance(charset, Charset):
            charset = Charset(charset)
        self._charset = charset
        if 'MIME-Version' not in self:
            self.add_header('MIME-Version', '1.0')
        if 'Content-Type' not in self:
            self.add_header('Content-Type', 'text/plain',
                            charset=charset.get_output_charset())
        else:
            self.set_param('charset', charset.get_output_charset())
        if charset != charset.get_output_charset():
            self._payload = charset.body_encode(self._payload)
        if 'Content-Transfer-Encoding' not in self:
            cte = charset.get_body_encoding()
            try:
                cte(self)
            except TypeError:
                self._payload = charset.body_encode(self._payload)
                self.add_header('Content-Transfer-Encoding', cte)