Exponential smoothing of values

def _smooth(values: List[float], beta: float) -> List[float]:
    """ Exponential smoothing of values """
    avg_value = 0.
    smoothed = []
    for i, value in enumerate(values):
        avg_value = beta * avg_value + (1 - beta) * value
        smoothed.append(avg_value / (1 - beta ** (i + 1)))
    return smoothed