I see an error in the main readme. In the documentation, the class "WhatsApp" have one argument the udid, but after some try, I see that the class wait two arguments, the udid and the app_package. You can check the following screenshot for more detail.

I see an error in the main readme. In the documentation, the class "WhatsApp" have one argument the udid, but after some try, I see that the class wait two arguments, the udid and the app_package. You can check the following screenshot for more detail.