bonze .back()
Returns the previous bonze instance in the chain - the selection that existed before the last traversal method. If there is no previous state, returns itself.
The key use case - act on a subset, then return
Apply an operation to a subset of elements, call .back(),
then act on a different subset - all in one chain.
item-1
item-2
item-3
item-4
item-5
item-6
// click a button
No previous state - returns itself
If .back() is called on the initial selection (no
traversal before it), it returns the same bonze instance - safe to
call at any depth.
item-1
item-2
item-3