code: function (publicInstance, callback, callerName) {
  	    ReactUpdateQueue.validateCallback(callback, callerName);
  	    var internalInstance = getInternalInstanceReadyForUpdate(publicInstance);
  
  	    // Previously we would throw an error if we didn't have an internal
  	    // instance. Since we want to make it a no-op instead, we mirror the same
  	    // behavior we have in other enqueue* methods.
  	    // We also need to ignore callbacks in componentWillMount. See
  	    // enqueueUpdates.
  	    if (!internalInstance) {
  	      return null;
  	    }
  
  	    if (internalInstance._pendingCallbacks) {
  	      internalInstance._pendingCallbacks.push(callback);
  	    } else {
  	      internalInstance._pendingCallbacks = [callback];
  	    }
  	    // TODO: The callback here is ignored when setState is called from
  	    // componentWillMount. Either fix it or disallow doing so completely in
  	    // favor of getInitialState. Alternatively, we can disallow
  	    // componentWillMount during server-side rendering.
  	    enqueueUpdate(internalInstance);
  	  }
docs: Enqueue a callback that will be executed after all the pending updates
  have processed.
  
  @param {ReactClass} publicInstance The instance to use as `this` context.
  @param {?function} callback Called after state is updated.
  @param {string} callerName Name of the calling function in the public API.
  @internal