# Modify list 
# Return copy of reference back to caller
def fun1(aListCopy):
    aListCopy[1] = aListCopy[1] * 2
    aListCopy[3] = aListCopy[3] * 2
    return aListCopy

# Modify list
# Because aList copy refers to the list in 'start()' the return
# isn't needed
def fun2(aListCopy):
    aListCopy[1] = aListCopy[1] * 2
    aListCopy[3] = aListCopy[3] * 2

# Make a new list that's local to 'fun3()'
# This time only the local list (fun3) changed
# The list in start is unchanged
def fun3(aListCopy):
    # aListCopy now refers to local list seperate from one in start()
    # Changes made only to local copy and not to the one in start()
    aListCopy = [1,2,3,4]
    aListCopy[1] = aListCopy[1] * 2
    aListCopy[3] = aListCopy[3] * 2
    print("Copy of list local only to fun3():\t", end="")
    print(aListCopy)



def start():
    aList = [1,2,3,4]
    print("Original list in start() before function calls:\t", end="")
    print(aList)
    aList = fun1(aList)    
    print("Original list in start() after calling fun1():\t", end="")
    print(aList)
    fun2(aList)
    print("Original list in start() after calling fun2():\t", end="")
    print(aList)
    fun3(aList)
    print("Original list in start() after calling fun3:\t", end="")
    print(aList)    

start()