code: def tokenize_ofp_instruction_arg(arg):
      
      arg_re = re.compile("[^,()]*")
      try:
          rest = arg
          result = []
          while len(rest):
              m = arg_re.match(rest)
              if m.end(0) == len(rest):
                  result.append(rest)
                  return result
              if rest[m.end(0)] == '(':
                  this_block, rest = _tokenize_paren_block(
                      rest, m.end(0) + 1)
                  result.append(this_block)
              elif rest[m.end(0)] == ',':
                  result.append(m.group(0))
                  rest = rest[m.end(0):]
              else:  # is ')'
                  raise Exception
              if len(rest):
                  assert rest[0] == ','
                  rest = rest[1:]
          return result
      except Exception:
          raise ryu.exception.OFPInvalidActionString(action_str=arg)
docs: Tokenize an argument portion of ovs-ofctl style action string.