Make #define work again. (Had accidentally omitted the keyword.)

            put("break", TOK_BREAK);

            put("return", TOK_RETURN);

            put("for", TOK_FOR);

            // TODO: remove these preprocessor-specific keywords. You should

            // be able to have symbols named pragma or define.

            put("pragma", TOK_PRAGMA);

            put("define", TOK_DEFINE);

        }

        ~KeywordTable() {