docs: def danger_unpack(regex):
      """
      Remove the outermost parens
  
      >>> unpack(r'(abc)')
      'abc'
      >>> unpack(r'(?:abc)')
      'abc'
      >>> unpack(r'(?P<xyz>abc)')
      'abc'
      >>> unpack(r'[abc]')
      '[abc]'
      """
  
      if is_packed(regex):
          return re.sub(r'^\((\?(:|P<.*?>))?(?P<content>.*?)\)$', r'\g<content>', regex)
      else:
          return regex