code: function() {
          var builder = [this.banner, '', this.options_title],
              shorts = false, longest = 0, rule;
          var rules = build_rules(this.filters, this._rules);
          for(var i = 0; i < rules.length; i++) {
              rule = rules[i];
              // Quick-analyze the options.
              if(rule.short) shorts = true;
              if(rule.decl.length > longest) longest = rule.decl.length;
          }
          for(var i = 0; i < rules.length; i++) {
              var text = spaces(6);
              rule = rules[i];
              if(shorts) {
                  if(rule.short) text = spaces(2) + rule.short + ', ';
              }
              text += spaces(rule.decl, longest) + spaces(3);
              text += rule.desc;
              builder.push(text);
          }
          return builder.join('\n');
      }
docs: Returns a string representation of this OptionParser instance.