the fact that lists and tuples are referential structures is significant to the semantics of these classes single list instance may include multiple references to the same object as elements of the listand it is possible for single object to be an element of two or more listsas those lists simply store references back to that object as an examplewhen you compute slice of listthe result is new list instancebut that new list has references to the same elements that are in the original listas portrayed in figure temp primes figure the result of the command temp primes[ : when the elements of the list are immutable objectsas with the integer instances in figure the fact that the two lists share elements is not that significantas neither of the lists can cause change to the shared object iffor examplethe command temp[ were executed from this configurationthat does not change the existing integer objectit changes the reference in cell of the temp list to reference different object the resulting configuration is shown in figure temp primes figure the result of the command temp[ upon the configuration portrayed in figure the same semantics is demonstrated when making new list as copy of an existing onewith syntax such as backup list(primesthis produces new list that is shallow copy (see section )in that it references the same elements as in the first list with immutable elementsthis point is moot if the contents of the list were of mutable typea deep copymeaning new list with new elementscan be produced by using the deepcopy function from the copy module