Python Crash Course exercise 8-11 - python-3.x

Question

I am working through the Python Crash Course book by Eric Matthes and I am stuck on 8-11. I don't quite understand how to return the new list and store it in a separate list.
So far I have tried to call the function by making a copy of the list.
def make_great(magicians):
"""This function adds the 'The Great' in front of a magicians name"""
great_magicians = [] #A new list to hold names of new magicians
while magicians: #This while loop runs while the parameter 'magicians' has elements in it
magician = magicians.pop() #Element from magicians parameter held in magician varibale
great_magician = magician + " the Great" #Creating a new element to store great_magician
great_magicians.append(great_magician) #Adding great_magicians to empty list
for great_magician in great_magicians: #Adding elements in great_magician back into magicians
magicians.append(great_magician)
magician_names1 = ['inho','mumbo jumbo','trick shotta','hwolla']
make_great(magician_names1[:])

Answer 1

List are mutable, that is they can be modified. so return the modified list and save it under the variable name of - magician_names1
def make_great(magicians):
"""This function adds the 'The Great' in front of a magicians name"""
great_magicians = [] #A new list to hold names of new magicians
while magicians: #This while loop runs while the parameter 'magicians' has elements in it
magician = magicians.pop() #Element from magicians parameter held in magician varibale
great_magician = magician + " the Great" #Creating a new element to store great_magician
great_magicians.append(great_magician) #Adding great_magicians to empty list
for great_magician in great_magicians: #Adding elements in great_magician back into magicians
magicians.append(great_magician)
return magicians
magician_names1 = ['inho','mumbo jumbo','trick shotta','hwolla']
magician_names1 = make_great(magician_names1[:])
print(magician_names1)

Answer 2

Your current function modifies the list you pass it in place. That means if you call make_great(magician_names1), it will modify the names in your main list and you won't have access to the original values any more.
If you want to make the changes in a new list, there are two general approaches you can take. The first is to change the function so that it creates and returns a new list and does not modify the list you passed in to it. That's pretty easy:
def make_great(magicians):
return [magician + " the Great" for magician in magicians]
# or:
# results = []
# for magician in magicians:
# results.append(magician + " the Great")
# return results
When you call it, you can assign the returned list to a new variable, and the old list will remain the same: great_names = make_great(magician_names1)
The other option is to leave your current function alone, as you might sometimes want to do the modifications in place. In the cases you don't want that, you can first make a copy, then modify the copy in place:
great_names = magician_names1[:] # make a copy and give it a name
make_great(great_names) # then modify the copied list in place
I'll note that while your current code does work for the in place modification, it's a lot more complicated than it needs to be (it also reverses the order the names appear in the list, which may be an undesireable side effect). You can write a much simpler version using the enumerate builtin function to get the index of a name as you iterate over the list it was contained in:
def make_great(magicians):
for i, name in enumerate(magicians):
magicians[i] = name + " the Great"