How do you change variables from def

Python Help
1

When I run the code, it says:

UnboundLocalError: cannot access local variable ‘selected’ where it is not associated with a value

Code:

import os
import time
import keyboard

selected = 1
options = 3

def draw():
    print("I will finish this after getting up() and down() to work...")
    pass

def up():
    time.sleep(0.01)
    os.system('cls' if os.name == 'nt' else 'clear')
        
    if selected == 1:
        selected = options
        draw()
    else:
        selected += 1
    print(selected)
pass

def down():
    time.sleep(0.01)
    os.system('cls' if os.name == 'nt' else 'clear')
    
    if selected == options:
        selected = 1
        draw()
    else:
        selected -= 1
    print(selected)
pass

keyboard.add_hotkey('up', lambda: up())
keyboard.add_hotkey('down', lambda: down())
keyboard.wait()

(Note: the draw() just print’s text for now so after getting up() and down() to work, I will then figure draw() out.

2 
 def up():
+    global selected
     time.sleep(0.01)
 
     os.system('cls' if os.name == 'nt' else 'clear')
     if selected == 1:
         selected = options
         draw()
     else:
         selected += 1
     print(selected)
 pass
 
 def down():
+    global selected
     time.sleep(0.01)
     os.system('cls' if os.name == 'nt' else 'clear')
 
     if selected == options:
         selected = 1
         draw()
     else:
         selected -= 1
     print(selected)
 pass
3

In the conditional statement:

if selected == 1:

it is referencing a variable that is neither global nor local.

4

This is happening because when Python compiles a function, if the function modifies any variables those variables are looked up in locals() instead of in globals(). You can override this behaviour with the global keyword as @effigies demonstrates.

5

Variables that are assigned to are local to the function unless declared global or nonlocal. This ‘selected += 1’ (or -= in the other function) makes selected a local, and the ‘if selected …’ before this attempts to access an unbound local.

6

Something confusing about the message is that it points to the comparison (this was Python 3.14)

if selected == 1:
       ^^^^^^^^
UnboundLocalError: cannot access local variable 'selected' where it is not associated with a value

Removing the assignments and leaving the comparison, there is no error.