docs: function proxy() {
      // cannot re-use cmd, modifiying breaks subsequent
      // method invocations must use a local variable
      var name = cmd
        , args = [].slice.call(arguments)
        , cb;
  
      if(typeof args[args.length - 1] === 'function') {
        cb = args.pop();
      }
      this.execute(cmd, args, cb);
      return this;
    }