CheckMembershipExistence.
        [Preview API] Check to see if a membership relationship between a container and subject exists.
        :param str subject_descriptor: The group or user that is a child subject of the relationship.
        :param str container_descriptor: The group that is the container in the relationship.

def check_membership_existence(self, subject_descriptor, container_descriptor):
        """CheckMembershipExistence.
        [Preview API] Check to see if a membership relationship between a container and subject exists.
        :param str subject_descriptor: The group or user that is a child subject of the relationship.
        :param str container_descriptor: The group that is the container in the relationship.
        """
        route_values = {}
        if subject_descriptor is not None:
            route_values['subjectDescriptor'] = self._serialize.url('subject_descriptor', subject_descriptor, 'str')
        if container_descriptor is not None:
            route_values['containerDescriptor'] = self._serialize.url('container_descriptor', container_descriptor, 'str')
        self._send(http_method='HEAD',
                   location_id='3fd2e6ca-fb30-443a-b579-95b19ed0934c',
                   version='5.1-preview.1',
                   route_values=route_values)