Push an element at the head of the list only if the list exists.
The key of the list.
One or more elements to push at the head of the list.
The length of the list after the push operation.
0
if the list did not exist and thus no element was pushed.
Push an element at the head of the list only if the list exists.
The key of the list.
One or more elements to push at the head of the list.
The length of the list after the push operation.
0
if the list did not exist and thus no element was pushed.