code: function (fn, ms, context) {
              ms = ms || 150;
              if (ms === -1) {
                  return function () {
                      fn.apply(context || this, arguments);
                  };
              }
              var last = util.now();
              return function () {
                  var now = util.now();
                  if (now - last > ms) {
                      last = now;
                      fn.apply(context || this, arguments);
                  }
              };
          }
docs: Throttles a call to a method based on the time between calls.
  @param {Function} fn The function call to throttle.
  @param {Object} [context] context fn to run
  @param {Number} [ms] The number of milliseconds to throttle the method call.
  Passing a -1 will disable the throttle. Defaults to 150.
  @return {Function} Returns a wrapped function that calls fn throttled.
  @member KISSY