code: function() {
                  var selectors = [], s, rules;
                  save();
  
                  s = $(this.selector);
                  while (s) {
                      selectors.push(s);
                      while ($(this.comment)) {
                          // do nothing
                      }
                      if (! $(',')) { break; }
                      while ($(this.comment)) {
                          // do nothing
                      }
                      s = $(this.selector);
                  }
                  if (s) {
                      while ($(this.comment)) {
                          // do nothing
                      }
                  }
  
                  if (selectors.length > 0 && (rules = $(this.block))) {
                      if (selectors.length === 1 &&
                          selectors[0].elements.length &&
                          selectors[0].elements[0].value === 'Map') {
                          var rs = new tree.Ruleset(selectors, rules);
                          rs.isMap = true;
                          return rs;
                      }
                      return new tree.Ruleset(selectors, rules);
                  } else {
                      // Backtrack
                      restore();
                  }
              }
docs: div, .class, body > p {...}