def _sendSetParameter(self, key, value, headers=None):
        target = '%s://%s:%s%s' % (self.factory.scheme, self.factory.host,
                                   self.factory.port, self.factory.path)
        if headers is None:
            headers = {}
        headers['Session'] = self.session
        headers[key] = value
        self.sendSetParameter(target, headers)