def __init__(self, steps, values):
    self.steps = steps
    self.values = values
    assert ((len(steps) + 1) == len(values)), 'There must be one more element in value as step.'
def __init__(self, steps, values):
    self.steps = steps
    self.values = values
    assert ((len(steps) + 1) == len(values)), 'There must be one more element in value as step.'