def on_response(self, message):
        # The following check ensures that if a callback is added for reading message from upstream, another one is not
        # added
        if not self.upstream.read_future:
            self.upstream.read_message(callback=self.on_response)
        if self.ws_connection:  # Check if connection still exists.
            if message.result():  # Check if it is not NULL (indirect checking of upstream connection).
                self.write_message(message.result())  # Write obtained message to client.
                self.store_downstream_data(message.result())
            else:
                self.close()
Returns an iterator of documents that shall be processed on the given
dataset/ETHPy150Open owtf/owtf/framework/http/proxy/proxy.py/CustomWebSocketHandler.on_response--crossover with--dataset/ETHPy150Open machinalis/iepy/iepy/data/db.py/DocumentManager.get_documents_lacking_preprocess