def METHOD_NAME(
        self, source_app_vertex, vertex_slice):
    """
    Creates a delay extension machine vertex and adds to the tracker.
    :param ~pacman.model.graphs.machine.MachineVertex source_vertex:
        The source of the delay
    :return: machine vertex
    :rtype: DelayExtensionMachineVertex
    """
    label = f"Delay extension for {source_app_vertex}"
    sdram = self.get_sdram_used_by_atoms()
    machine_vertex = DelayExtensionMachineVertex(
        sdram, label, vertex_slice, self.governed_app_vertex)
    self._machine_vertex_by_slice[vertex_slice] = machine_vertex
    return machine_vertex