code: function(path) {
      var index = this;
      if (path !== null) {
        for (var i = 0; i < path.length; i++) {
          var id = path[i];
          index.scopes[id] = index.scopes[id] || { nodes: {}, scopes: {} };
          index = index.scopes[id];
        }
      }
      return index;
    }
docs: Resolves a sub-hierarchy of the index via a given path --------