def normalize(tensor, mean, std):
    """Normalize a ``torch.tensor``

    Args:
        tensor (torch.tensor): tensor to be normalized.
        mean: (list): the mean of BGR
        std: (list): the std of BGR
    
    Returns:
        Tensor: Normalized tensor.
    """

    for t, m, s in zip(tensor, mean, std):
        t.sub_(m).div_(s)
    return tensor