words_in (string, (p_string word) {
                                    ...
                                  });

words_in (string, (int index, p_string word) {
                                               ...
                                             });

words_in (string, spaces, (p_string word) {
                                            ...
                                          });

words_in (string, spaces, (int index, p_string word) {
                                                       ...
                                                     });
