def METHOD_NAME(module, _):
    """send this module to GPU; send whatever tracked module was previous in GPU to CPU;
    we add this as forward_pre_hook to a lot of modules and this way all but one of them will
    be in CPU
    """
    global module_in_gpu
    module = parents.get(module, module)
    if module_in_gpu == module:
        return
    if module_in_gpu is not None:
        module_in_gpu.to(cpu)
    module.to(devices.device)
    module_in_gpu = module