cerr << "   case 'n': start new search                        " << endl;
cerr << "   case 's': search for string in author or title    " << endl;
cerr << "   case 'f': read a catalog from a file              " << endl;
cerr << "   case 'u': undo last change to results             " << endl;
cerr << "   case 'r': show results                            " << endl;
cerr << "   case 'c': show catalog                            " << endl;
cerr << "   case 'b': 'browse', e.g., if the user types       " << endl;
cerr << "                         b 7                         " << endl;
cerr << "             then a list gets displayed of the       " << endl;
cerr << "             7th book in the current list of         " << endl;
cerr << "             search results plus the five books      " << endl;
cerr << "             that sit on either side of it on        " << endl;
cerr << "             the library shelf                       " << endl;
cerr << "   case 'q': quit                                    " << endl;