html_scanner:

  class html_scanner: public lex_scanner {
  public:
          html_scanner(istream* in = &cin, ostream* out = &cout )
                                                  : lex_scanner(in,out) {
                  in_cmt = 0;
          }
          ~html_scanner() { cout << "Ending html" << endl; }
          term* operator()();
  private:
  int in_cmt;
  };