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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 master_tops(self):
        '''
        Return the metadata derived from the master_tops system
        '''
        log.debug(
            'The _ext_nodes master function has been renamed to _master_tops. '
            'To ensure compatibility when using older Salt masters we will '
            'continue to invoke the function as _ext_nodes until the '
            'Magnesium release.'
        )
        # TODO: Change back to _master_tops
        # for Magnesium release
        load = {'cmd': '_ext_nodes',
                'id': self.opts['id'],
                'opts': self.opts}
        if self.auth:
            load['tok'] = self.auth.gen_token(b'salt')
        return salt.utils.data.decode(self.channel.send(load)) if six.PY2 \
            else self.channel.send(load)