Threaded code not giving output for some reason (pynput)

Question

I'm testing this code from this response However I'm getting nothing in my output! Does anyone know why? My goal is to have a loop start when a key is pressed down and end when it's released. For some reason I can't get it to work.

from pynput.keyboard import Listener, KeyCode
import time

# --- functions ---

def get_pressed(event):
    global key_a # inform function to use external/global variable instead of local one

    if event == KeyCode.from_char('a'):
        key_a = True

def get_released(event):
    global key_a

    if event == KeyCode.from_char('a'):
        key_a = False

# --- main --

key_a = False  # default value at start 

listener = Listener(on_press=get_pressed, on_release=get_released)
listener.start() # start thread with listener

while True:

    if key_a:
        print('hold pressed: a')

    time.sleep(.1)  # slow down loop to use less CPU

listener.stop() # stop thread with listener
listener.join() # wait till thread ends work