def METHOD_NAME(self, run_state, path, stream_fn, reply_fn):
    """
    Given a run state, a path, a stream function and a reply function,
        - Computes the real filesystem path to the path in the bundle
        - In case of error, invokes reply_fn with an http error
        - Otherwise starts a thread calling stream_fn on the computed final path
    """
    try:
        final_path = get_target_path(
            run_state.bundle_path, BundleTarget(run_state.bundle.uuid, path)
        )
    except PathException as e:
        reply_fn((http.client.NOT_FOUND, str(e)), None, None)
    read_thread = threading.Thread(target=stream_fn, args=[final_path])
    read_thread.start()
    self.read_threads.append(read_thread)