undo / redo feature

Thanks all for this fantastic platform. One very obvious feature I am missing and which isn't even posted so far is "undo" (CTRL + Z). Deleted a layer you want back? Undo. Deleted a data set you want back? Undo. Changed a bunch of visuals to test different styles out? Undo, undo, undo. Of course, once you have undo, you can also think about a redo function. Any thoughts?