How to account for all user inputs with a cleaner code?

Question

New to Python and writing a simple text-based game. I am trying to account for both invalid user input and unavailable options. I have created a while loop that is functional - but messy. Any guiding lights for a cleaner way to do this? I have tried using the 'or' option to combine the main while loops and simply change the response(invalid/unavailable) based on the condition, but it wouldn't work at all - not really sure why either. for reference, I am using dictionaries to create the conditions and the user function choose_dir() to return a user input for user_dir.*

def change_room():
    choose_dir()
    # FIXME
    while user_dir not in ['N', 'S', 'E', 'W']:
        print("Invalid entry.")
        choose_dir()
    else:
        while rooms[current_room][user_dir] == 'None':
            print("Can't go that way.")
            choose_dir()
            while user_dir not in ['N', 'S', 'E', 'W']:
                print("Invalid entry.")
                choose_dir()

Answer 1

Use a single loop, not all these nested if and loops. In your code, if the user chooses a direction that leads to None in the last call to choose_dir(), it won't detect that.

def change_room():
    while True:
        choose_dir()
        if user_dir not in ['N', 'S', 'E', 'W']:
            print("Invalid entry.")
        elif rooms[current_room][user_dir] == 'None':
            print("Can't go that way.")
        else:
            return rooms[current_room][user_dir]

BTW, it would be better if choose_dir() returned the chosen direction, rather than using the global variable user_dir.