undefined method yii\helpers\StringHelper::explode()


I have Yii 2.0.2 dev.

I did not have method explode() in BaseStringHelpers. Problem solved by copying the code from github.

But i would like to understand, where was the problem?

I had done composer update and self-update.

This method has been added in 2.0.4 version which is not released yet.

Thanks a lot.

ps. for me, this method worked perfectly.