code: def parse(s):
          
          if isinstance(s, arg_type):
              return s
          if isinstance(s, (list, tuple)):
              for arg in arg_type:
                  if [s[0], s[-1]] == arg.delims():
                      return arg(*s[1:-1])
              raise TypeError('Malformed argument. First and last elements must '
                              'match a valid argument format. In this case, TexSoup'
                              ' could not find matching punctuation for: %s.\n'
                              'Common issues include: Unescaped special characters,'
                              ' mistyped closing punctuation, misalignment.' % (str(s)))
          for arg in arg_type:
              if arg.__is__(s):
                  return arg(arg.__strip__(s))
          raise TypeError('Malformed argument. Must be an Arg or a string in '
                          'either brackets or curly braces.')
docs: Parse a string or list and return an Argument object
  
          :param Union[str,iterable] s: Either a string or a list, where the first and
              last elements are valid argument delimiters.
  
          >>> Arg.parse(RArg('arg0'))
          RArg('arg0')
          >>> Arg.parse('[arg0]')
          OArg('arg0')