def normalize(X, mean=None, std=None):
    if mean is None or std is None:
        mean = X.mean(0)
        std = X.std(0)
    return (X - mean) / std
Normalize X. If mean OR std is None, normalizes
dataset/ETHPy150Open CamDavidsonPilon/lifelines/lifelines/utils/__init__.py/normalize