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import torch


def to_device_async(tensor, device):
    return tensor.to(device, non_blocking=True)


def to_gpu_async(cpu_tensor):
    return cpu_tensor.to('cuda', non_blocking=True)


def to_cpu_numpy(gpu_tensor):
    if not isinstance(gpu_tensor, torch.Tensor):
        return gpu_tensor
    return gpu_tensor.detach().cpu().numpy()

def remove_module_in_state_dict(state_dict):
    """
    If model is saved with DataParallel, checkpoint keys is started with 'module.' remove it and return new state dict
    :param checkpoint:
    :return: new checkpoint
    """
    new_state_dict = {}
    for key, val in state_dict.items():
        new_key = key.replace('module.', '')
        new_state_dict[new_key] = val
    return new_state_dict
