periods

def divide(a, b, dividends=[], period=[], is_fractional_part=0):
    # if current dividend is was already
    # processed, return nums of period
    if a in dividends:
        return period

    dividends.append(a)

    # we set is_fractional_part to 1 once
    # and for good if dividend is less than divider.
    # we append zero as a num of period and call
    # divide() again with new period and dividends
    if a < b:
        is_fractional_part = 1

        period = divide((a * 10), b, dividends, period, is_fractional_part)
        return period

    # if a and b is the same num, frac is not periodical
    # we just return period
    if a is b:
        return period

    # if a is less than b we check if we processing frac part of a num
    # otherwise we append nothing to period
    # then we call the divide() func with a result of integer division a by b
    if a > b:
        if is_fractional_part:
            period.append(a // b)
        period = divide((a % b), b, dividends, period, is_fractional_part)
        return period


period_of_frac = list(divide(20, 3))

print(period_of_frac)