def __call__(self, *args, **kwargs):
        """
        converts ``values()`` into a string value

        This method converts the results of ``values()`` into a string
        value for common usage.  By default, it is asserted that only
        one value exists; if you need to access all values then either
        call ``values()`` directly, or inherit ``_MultiValueHeader``
        which overrides this method to return a comma separated list of
        values as described by section 4.2 of RFC 2616.
        """
        values = self.values(*args, **kwargs)
        assert isinstance(values, (tuple, list))
        if not values:
            return ''
        assert len(values) == 1, repr(values) % "more than one value: %s"
        return str(values[0]).strip()
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Paste-2.0.1/paste/httpheaders.py/HTTPHeader.__call__/swapped operands of `%`