update an export

def update(self, volume_id, **kwargs):
        """
        update an export
        """
        # These arguments are allowed
        self.allowed('update', kwargs,
                     ['status', 'instance_id',
                      'mountpoint', 'ip', 'initiator', 'session_ip',
                      'session_initiator'])
        # Remove parameters that are None
        params = self.unused(kwargs)
        return self.http_post('/volumes/%s/export' % volume_id, params=params)