gistfile1.py

listA = [1,2,3,4]   #listA now holds a refrence to a list object
listB = listA       #a refrence to the refrence held by listA
listC = list(listA) #a new copy of the object reffered to in the refrence held by listA
listA.append('dog') #update the object reffered to in the refrence held by listA
print(listB)        #a refrence to the refrence held by listA -> the object reffered to in the refrence held by listA
print(listC)        #the copy we made before updating is, of course, unchanged