Added a note about concurrency

    @doc_response(200, mimetype="multipart/x-mixed-replace")

    def get(self):

        """

        MJPEG stream from the microscope camera

        MJPEG stream from the microscope camera.

        Note: While the code actually getting frame data from a camera and storing it in

        camera.frame runs in a thread, the gen(microscope.camera) generator does not.

        This response is therefore blocking. The generator just yields the most recent

        frame from the camera object, passed to the Flask response, and then repeats until

        the connection is closed.

        Without monkey patching with gevent, or using a native threaded server, the stream

        will block all proceeding requests.

        """

        microscope = find_component("org.openflexure.microscope")

        # Restart stream worker thread