def fields(self, fields):
        """Sets `sysparm_fields` after joining the given list of `fields`

        :param fields: List of fields to include in the response
        :raise:
            :InvalidUsage: if fields is of an unexpected type
        """

        if not isinstance(fields, list):
            raise InvalidUsage('fields must be of type `list`')

        self._sysparms['sysparm_fields'] = ",".join(fields)
Sets `sysparm_fields` after joining the given list of `fields`

        :param fields: List of fields to include in the response
        :raise:
            :InvalidUsage: if fields is of an unexpected type