How to use the textfsm.parser.TextFSMRule function in textfsm

# Finish rules processing on blank line.
      if not line:
        break
      if not isinstance(line, six.string_types):
        line = line.decode('utf-8')
      if self.comment_regex.match(line):
        continue

      # A rule within a state, starts with 1 or 2 spaces, or a tab.
      if not line.startswith((' ^', '  ^', '\t^')):
        raise TextFSMTemplateError(
            "Missing white space or carat ('^') before rule. Line: %s" %
            self._line_num)

      self.states[state_name].append(
          TextFSMRule(line, self._line_num, self.value_map))

    return state_name

return

    state_name = ''
    # Strip off extra white space lines (including comments).
    for line in template:
      self._line_num += 1
      line = line.rstrip()
      if not isinstance(line, six.string_types):
        line = line.decode('utf-8')
      # First line is state definition
      if line and not self.comment_regex.match(line):
         # Ensure statename has valid syntax and is not a reserved word.
        if (not self.state_name_re.match(line) or
            len(line) > self.MAX_NAME_LEN or
            line in TextFSMRule.LINE_OP or
            line in TextFSMRule.RECORD_OP):
          raise TextFSMTemplateError("Invalid state name: '%s'. Line: %s"
                                     % (line, self._line_num))

        state_name = line
        if state_name in self.states:
          raise TextFSMTemplateError("Duplicate state name: '%s'. Line: %s"
                                     % (line, self._line_num))
        self.states[state_name] = []
        self.state_list.append(state_name)
        break

    # Parse each rule in the state.
    for line in template:
      self._line_num += 1
      line = line.rstrip()

if not template:
      return

    state_name = ''
    # Strip off extra white space lines (including comments).
    for line in template:
      self._line_num += 1
      line = line.rstrip()
      if not isinstance(line, six.string_types):
        line = line.decode('utf-8')
      # First line is state definition
      if line and not self.comment_regex.match(line):
         # Ensure statename has valid syntax and is not a reserved word.
        if (not self.state_name_re.match(line) or
            len(line) > self.MAX_NAME_LEN or
            line in TextFSMRule.LINE_OP or
            line in TextFSMRule.RECORD_OP):
          raise TextFSMTemplateError("Invalid state name: '%s'. Line: %s"
                                     % (line, self._line_num))

        state_name = line
        if state_name in self.states:
          raise TextFSMTemplateError("Duplicate state name: '%s'. Line: %s"
                                     % (line, self._line_num))
        self.states[state_name] = []
        self.state_list.append(state_name)
        break

    # Parse each rule in the state.
    for line in template:
      self._line_num += 1
      line = line.rstrip()