The remaining cases are '(' and ')'. We handle '(' by skipping the
reduction phase completely. ')' is given lower priority than
everything else, including '(', effectively forcing a reduction of the
-parenthesised expression. If there is a matching '(', the routine
+parenthesized expression. If there is a matching '(', the routine
reduce() exits immediately. If the normal exit route sees a ')', then
there cannot have been a matching '(' and an error message is output.