whole_func_string: function(expr, context, subIntegral) {
        if(expr.type === 'ParenthesisNode') {
          var int = subIntegral(expr.content, context, "parentheses removal");
          return int ? new ParenthesisNode(int) : null;
        }
      }
func_code_string: function(expr, context, subIntegral) {
        if(expr.type === 'ParenthesisNode') {
          var int = subIntegral(expr.content, context, "parentheses removal");
          return int ? new ParenthesisNode(int) : null;
        }
      }
func_documentation_string: Ignore parentheses