def list_instances(
        self,
        parent,
        page_token=None,
        retry=google.api_core.gapic_v1.method.DEFAULT,
        timeout=google.api_core.gapic_v1.method.DEFAULT,
        metadata=None,
    ):
        """
        Lists information about instances in a project.

        Example:
            >>> from google.cloud import bigtable_admin_v2
            >>>
            >>> client = bigtable_admin_v2.BigtableInstanceAdminClient()
            >>>
            >>> parent = client.project_path('[PROJECT]')
            >>>
            >>> response = client.list_instances(parent)

        Args:
            parent (str): The unique name of the project for which a list of instances is
                requested. Values are of the form ``projects/<project>``.
            page_token (str): DEPRECATED: This field is unused and ignored.
            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.bigtable_admin_v2.types.ListInstancesResponse` 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 "list_instances" not in self._inner_api_calls:
            self._inner_api_calls[
                "list_instances"
            ] = google.api_core.gapic_v1.method.wrap_method(
                self.transport.list_instances,
                default_retry=self._method_configs["ListInstances"].retry,
                default_timeout=self._method_configs["ListInstances"].timeout,
                client_info=self._client_info,
            )

        request = bigtable_instance_admin_pb2.ListInstancesRequest(
            parent=parent, page_token=page_token
        )
        if metadata is None:
            metadata = []
        metadata = list(metadata)
        try:
            routing_header = [("parent", parent)]
        except AttributeError:
            pass
        else:
            routing_metadata = google.api_core.gapic_v1.routing_header.to_grpc_metadata(
                routing_header
            )
            metadata.append(routing_metadata)

        return self._inner_api_calls["list_instances"](
            request, retry=retry, timeout=timeout, metadata=metadata
        )