Undo Button

I think there should be an undo button for last moves. Sometimes i mean to play one way but because a mistake move i end up having to change my plan. Also, sometimes we are quick to look and right before you move; you realize that there was a power move that you could have made but is too late because you can't go back. This is why i think the one move back or prior move button should be created. Thanks. I am not sure if anyone had this idea before but i am new here lolz