Calling a recursive function using the alphabet

Question

I'm supposed to write a statement that calls the recursive function backwards_alphabet() with input starting_letter. I've figured out how to do that. The problem is that at the end of my code it prints None. How do I get it to stop doing that?

(Anything above starting_letter = input() cannot be edited or added on to. I've tried and the site I'm using won't let me)

Here is my code

def backwards_alphabet(curr_letter):
    if curr_letter == 'a':
        print(curr_letter)
    else:
        print(curr_letter)
        prev_letter = chr(ord(curr_letter) - 1)
        backwards_alphabet(prev_letter)

starting_letter = input()

print(backwards_alphabet(starting_letter))

The expected output is supposed to be f e d c b a

My output is f e d c b a None

All I had to do was get rid of print

Answer 1

Your code is correct, your problem is:

print(backwards_alphabet(starting_letter))

You're trying to print the function, which returns None as there is no return statement in the function.

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Your code can also be simplified:

def backwards_alphabet(curr_letter: str):
    if curr_letter != '`':
        print(curr_letter)
        backwards_alphabet(chr(ord(curr_letter) - 1))

When you have to write a recursive function, always start by thinking what will the base condition be?