SCM mod = lexer_->set_current_scope ();
SCM parser = lexer_->lookup_identifier_symbol (ly_symbol2scm ("parser"));
lexer_->set_identifier (ly_symbol2scm ("parser"), self_scm ());
SCM mod = lexer_->set_current_scope ();
SCM parser = lexer_->lookup_identifier_symbol (ly_symbol2scm ("parser"));
lexer_->set_identifier (ly_symbol2scm ("parser"), self_scm ());