code: function(path) {
      var p = path || this.path(); 
      var pp = (!p || p == "/")? null : p.substring(0, p.lastIndexOf("/"));
      return (pp=="")? "/" : pp;
    }
docs: SpahQL#parentPath() -> String or null
  
  Returns the parent path for the first item in this set, or null if this item is the root.
  For instance, a result with path "/foo/bar/baz" has parent path "/foo/bar"