code: def t_DATE(t):
      r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
      day = int(t.lexer.lexmatch.group('day'))
      month = int(t.lexer.lexmatch.group('month'))
      year = int(t.lexer.lexmatch.group('year'))
      t.value = date(year, month, day)
      return f t_DATE(t):
      r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
      day = int(t.lexer.lexmatch.group('day'))
      month = int(t.lexer.lexmatch.group('month'))
      year = int(t.lexer.lexmatch.group('year'))
      t.value = date(year, month, day)
      return t
docs: r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})