code: function() {
                  var node, root = [];
  
                  while ((node = $(this.rule) || $(this.ruleset) ||
                                 $(this.comment)) ||
                                 $(/^[\s\n]+/) || (node = $(this.invalid))) {
                      if (node) root.push(node);
                  }
                  return root;
              }
docs: The `primary` rule is the *entry* and *exit* point of the parser. The rules here can appear at any level of the parse tree.  The recursive nature of the grammar is an interplay between the `block` rule, which represents `{ ... }`, the `ruleset` rule, and this `primary` rule, as represented by this simplified grammar:  primary  →  (ruleset | rule)+ ruleset  →  selector+ block block    →  '{' primary '}'  Only at one point is the primary rule not called from the block rule: at the root level.