code: function () {
                  var node, root = [];
  
                  while ((node = $(this.mixin.definition) || $(this.rule)    ||  $(this.ruleset) ||
                                 $(this.mixin.call)       || $(this.comment) ||  $(this.directive))
                                 || $(/^[\s\n]+/)) {
                      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.