var $ = rig.builder({
   'string' : {
     capitalize: function () {
       return this.charAt(0).toUpperCase() + this.substr(1);
     }
   },
   'array' : {
     compact: function () {
       var result = [];
       for (var i = 0; i < this.length; i++) {
         if (this[i]) result.push(this[i]);
       }
       return result;
     }
   }
});

$("rig").capitalize();                   // "Rig"
$(["hello", "", "world", ""]).compact(); // ["hello", "world"]