async def list_processors_async(self, project_id: str) -> list[quantum.QuantumProcessor]:
        """Returns a list of Processors that the user has visibility to in the
        current Engine project. The names of these processors are used to
        identify devices when scheduling jobs and gathering calibration metrics.

        Args:
            project_id: A project_id of the parent Google Cloud Project.

        Returns:
            A list of metadata of each processor.
        """
        request = quantum.ListQuantumProcessorsRequest(parent=_project_name(project_id), filter='')
        return await self._send_list_request_async(
            self.grpc_client.list_quantum_processors, request
        )
Returns a list of Processors that the user has visibility to in the
        current Engine project. The names of these processors are used to
        identify devices when scheduling jobs and gathering calibration metrics.

        Args:
            project_id: A project_id of the parent Google Cloud Project.

        Returns:
            A list of metadata of each processor.
        
cirq-google/cirq_google/engine/engine_client.py