Advent of code 2022 day 25

def day25(s):

  def from_snafu(text):
    return functools.reduce(lambda n, ch: n * 5 + '=-012'.index(ch) - 2, text, 0)

  def to_snafu(n):
    b = []
    while n != 0:
      n, mod = divmod(n + 2, 5)
      b.append('=-012'[mod])
    return ''.join(b[::-1])

  total = sum(from_snafu(line) for line in s.splitlines())
  return to_snafu(total)