code: function(f)
      {
          var q = this.clone();
  
          if (arguments.length > 1)
              q._fields = _(arguments).toArray();
          else if (f)
              q._fields = _(f).isArray() ? f : [f];
          else
              q._fields = Queryable.getFields(this._T);
  
          return q;
      }
docs: Set what fields we will be using