Export a remote function.

        Args:
            remote_function: the RemoteFunction object.

def export(self, remote_function):
        """Export a remote function.

        Args:
            remote_function: the RemoteFunction object.
        """
        if self._worker.mode is None:
            # If the worker isn't connected, cache the function
            # and export it later.
            self._functions_to_export.append(remote_function)
            return
        if self._worker.mode != ray.worker.SCRIPT_MODE:
            # Don't need to export if the worker is not a driver.
            return
        self._do_export(remote_function)