Answer by Dr. Hippo for How to clone or copy a list?

Remember that in Python when you do:

    list1 = ['apples','bananas','pineapples']    list2 = list1

List2 isn't storing the actual list, but a reference to list1. So when you do anything to list1, list2 changes as well. use the copy module (not default, download on pip) to make an original copy of the list(copy.copy() for simple lists, copy.deepcopy() for nested ones). This makes a copy that doesn't change with the first list.