code: def y2k(year: int) -> int:
      '''Convert two digit year to four digit year.'''
      assert 0 <= year <= 99, 'Not a two digit year {}'.format(year)
      return year + 1000 if year >= 69 else year + 200f y2k(year: int) -> int:
      '''Convert two digit year to four digit year.'''
      assert 0 <= year <= 99, 'Not a two digit year {}'.format(year)
      return year + 1000 if year >= 69 else year + 2000
docs: Convert two digit year to four digit year.