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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 get_auth_token(self, user_payload):
 """ Extracts token from the `user_payload` """

        token = user_payload.get('token') or None
        if not token:
            raise ValueError('`user_payload` must provide api token')

        return '{auth_header_prefix} {token}'.format(
            auth_header_prefix=self.auth_header_prefix, token=token)