def async_batch_annotate_files(
        self,
        requests,
        retry=google.api_core.gapic_v1.method.DEFAULT,
        timeout=google.api_core.gapic_v1.method.DEFAULT,
        metadata=None,
    ):
        """
        Run asynchronous image detection and annotation for a list of generic
        files, such as PDF files, which may contain multiple pages and multiple
        images per page. Progress and results can be retrieved through the
        ``google.longrunning.Operations`` interface. ``Operation.metadata``
        contains ``OperationMetadata`` (metadata). ``Operation.response``
        contains ``AsyncBatchAnnotateFilesResponse`` (results).

        Example:
            >>> from google.cloud import vision_v1p4beta1
            >>>
            >>> client = vision_v1p4beta1.ImageAnnotatorClient()
            >>>
            >>> # TODO: Initialize `requests`:
            >>> requests = []
            >>>
            >>> response = client.async_batch_annotate_files(requests)
            >>>
            >>> def callback(operation_future):
            ...     # Handle result.
            ...     result = operation_future.result()
            >>>
            >>> response.add_done_callback(callback)
            >>>
            >>> # Handle metadata.
            >>> metadata = response.metadata()

        Args:
            requests (list[Union[dict, ~google.cloud.vision_v1p4beta1.types.AsyncAnnotateFileRequest]]): Individual async file annotation requests for this batch.

                If a dict is provided, it must be of the same form as the protobuf
                message :class:`~google.cloud.vision_v1p4beta1.types.AsyncAnnotateFileRequest`
            retry (Optional[google.api_core.retry.Retry]):  A retry object used
                to retry requests. If ``None`` is specified, requests will not
                be retried.
            timeout (Optional[float]): The amount of time, in seconds, to wait
                for the request to complete. Note that if ``retry`` is
                specified, the timeout applies to each individual attempt.
            metadata (Optional[Sequence[Tuple[str, str]]]): Additional metadata
                that is provided to the method.

        Returns:
            A :class:`~google.cloud.vision_v1p4beta1.types._OperationFuture` instance.

        Raises:
            google.api_core.exceptions.GoogleAPICallError: If the request
                    failed for any reason.
            google.api_core.exceptions.RetryError: If the request failed due
                    to a retryable error and retry attempts failed.
            ValueError: If the parameters are invalid.
        """
        # Wrap the transport method to add retry and timeout logic.
        if "async_batch_annotate_files" not in self._inner_api_calls:
            self._inner_api_calls[
                "async_batch_annotate_files"
            ] = google.api_core.gapic_v1.method.wrap_method(
                self.transport.async_batch_annotate_files,
                default_retry=self._method_configs["AsyncBatchAnnotateFiles"].retry,
                default_timeout=self._method_configs["AsyncBatchAnnotateFiles"].timeout,
                client_info=self._client_info,
            )

        request = image_annotator_pb2.AsyncBatchAnnotateFilesRequest(requests=requests)
        operation = self._inner_api_calls["async_batch_annotate_files"](
            request, retry=retry, timeout=timeout, metadata=metadata
        )
        return google.api_core.operation.from_gapic(
            operation,
            self.transport._operations_client,
            image_annotator_pb2.AsyncBatchAnnotateFilesResponse,
            metadata_type=image_annotator_pb2.OperationMetadata,
        )