First argument of event_key() must be a one letter string, or "up", "down", "left", "right", or "space". on line: 82

def set_up_track():
    """Use a function to create a maze or race track"""
    stage.set_background_color("black")
    rec1 = codesters.Rectangle(20, 240, 450, 25, "purple")
    rec2 = codesters.Rectangle(-25, -240, 450, 25, "purple")
    rec3 = codesters.Rectangle(-100, 160, 400, 25, "purple")
    rec4 = codesters.Rectangle(25, -160, 450, 25, "purple")
    rec5 = codesters.Rectangle(100, 80, 600, 25, "purple")
    rec6 = codesters.Rectangle(-100, -80, 350, 25, "purple")
    rec7 = codesters.Rectangle(40, 0, 300, 25, "purple")
    rec8 = codesters.Rectangle(177, -50, 25, 85, "purple")
    rec9 = codesters.Rectangle(110, 160, 25, 55, "purple")
    
    # Modified part of the maze
    rec10 = codesters.Rectangle(150, -50, 25, 85, "purple")
    rec11 = codesters.Rectangle(-150, -50, 25, 85, "purple")
    
    rec_win = codesters.Rectangle(-225, 240, 50, 25, "red")  # Keep the goal area color as red

def add_sprites():
    """ This will be the sprites that traverse the maze. """
    player = codesters.Sprite("ufo", 235, -240)
    player.set_size(0.2)
    
    enemy = codesters.Sprite("alien3", -235, 240)
    enemy.set_size(0.2)
    
    return player, enemy

def move_left(event):
    """ This moves the player sprite to the left """
    player.move_left(10)

def move_right(event):
    """ This moves the player sprite to the right """
    player.move_right(10)

def move_up(event):
    """ This moves the player sprite up """
    player.move_up(10)

def move_down(event):
    """ This moves the player sprite down """
    player.move_down(10)

def enemy_movement():
    """ This controls the movement of the enemy sprite """
    enemy.set_x(enemy.get_x() + 5)

def track_collision(sprite, hit_sprite):
    """ Function to detect collisions on the player sprite with the track or target win area"""
    my_var = hit_sprite.get_color()
    if my_var == "purple":
        player.say("Track hit! Start over", 0.5)
        player.go_to(235, -240)
    elif my_var == "red":
        player.say("Goal!", 2)

def enemy_collision(player, enemy):
    """ Function to detect collisions between player and enemy sprites """
    player.say("Enemy hit! Lose a life", 1)
    player.go_to(235, -240)

def start_countdown():
    """ Function to display countdown before the game starts """
    for i in range(3, 0, -1):
        countdown = codesters.Text(str(i), 0, 0, "white")
        time.sleep(1)
        countdown.hide()
    countdown = codesters.Text("Go!", 0, 0, "white")
    time.sleep(1)
    countdown.hide()

def main():
    """ Sets up the program and calls other functions """
    set_up_track()
    player, enemy = add_sprites()
    player.event_collision(track_collision)
    enemy.event_collision(enemy_collision)
    
    # Use different functions for player sprite movement
    stage.event_key("left arrow", move_left)
    stage.event_key("right arrow", move_right)
    stage.event_key("up arrow", move_up)
    stage.event_key("down arrow", move_down)

    # Countdown before the game starts
    start_countdown()

    # Interval event to control the movement of the enemy sprite
    stage.event_interval(enemy_movement, 1)

main()