Formatting any positive integer to roman numerals

roman.py

def roman(num: int) -> str:

    chlist = "VXLCDM"
    rev = [int(ch) for ch in reversed(str(num))]
    chlist = ["I"] + [chlist[i % len(chlist)] + "\u0304" * (i // len(chlist))
                      for i in range(0, len(rev) * 2)]

    def period(p: int, ten: str, five: str, one: str) -> str:
        if p == 9:
            return one + ten
        elif p >= 5:
            return five + one * (p - 5)
        elif p == 4:
            return one + five
        else:
            return one * p

    return "".join(reversed([period(rev[i], chlist[i * 2 + 2], chlist[i * 2 + 1], chlist[i * 2])
                             for i in range(0, len(rev))]))