docs: function(key, obj) {
      var t = this.objectType(obj);
      if(t == "array") {
        var k = parseInt(key);
        return isNaN(k)? null : k;
      }
      else if(t == "object") {
        var k = key.toString();
        return (k.match(/^\s*$/))? null : k;
      }
      return null;
    }