def expected_lift(variations, control=None):
    """Calculate expected lift E[(B-A)/A]."""
    values = OrderedDict()
    control, others = _split(variations, control)
    a = control.posterior
    m = a.mean()
    for label, variation in others.items():
        b = variation.posterior
        lift = m / (b.mean()-m)
        values[label] = lift

    return values
dataset/ETHPy150Open bogdan-kulynych/trials/trials/stats.py/expected_lift/swapped operands of `/`