Dungeon Game : get_locations(), "monster not defined" argh!

import random
import os
import sys

CELLS = [(0,0),(1,0),(2,0),(3,0),(4,0),
         (0,1),(1,1),(2,1),(3,1),(4,1),
         (0,2),(1,2),(2,2),(3,2),(4,2),
         (0,3),(1,3),(2,3),(3,3),(4,3),
         (0,4),(1,4),(2,4),(3,4),(4,4),]

def clear_screen():
    if os.name == 'nt':
        os.system('cls')
    else: os.system('clear')

def get_locations():
    random.sample(CELLS,3)
    return monster, door, player


def move_player(player, move):
    #ascertain current player location
    #if move == LEFT, x-1
    #if move == RIGHT, x+1
    #if move == UP, y-1
    #if move == DOWN, y+1
    return player

def get_move(player):
    move = ["LEFT", "RIGHT", "UP", "DOWN"]
    x, y = player
    if x == 0:
        move.remove("LEFT")
    if x == 4:
        move.remove("RIGHT")
    if y == 0:
        move.remove("UP")
    if y == 4:
        move.remove("DOWN")
    return move



monster, door, player  = get_locations()

while True:
    print("Welcome to the DUNGEON !")
    print("You are currently in room {}".format(player)) 
    print("You can move {}".format(", ".join(get_move(player))))
    print("Enter QUIT to quit")

    move = input("> ")
    move = move.upper()
    if move == 'QUIT':
        print("I guess you were afraid of the DUNGEON!")
        break