Player not defined

import random

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

def get_locations():
    monster = random.choice(CELLS)
    door = random.choice(CELLS)
    start = random.choice(CELLS)

    if monster == door or monster == start or door == start:
        return get_locations()

    return monster, door, start 





def move_player(player, move):
    x, y = player
    if move == 'LEFT':
        y -= 1
    elif move == 'RIGHT':
        y += 1
    elif move == 'UP':
        x -= 1
    elif move == 'DOWN':
        x += 1

    return x,y


def get_moves(player):
    moves = ['LEFT', 'RIGHT', 'UP', 'DOWN']

    if player[1] == 0:
        moves.remove('LEFT')
    if player[1] == 2:
        moves.remove('RIGHT')
    if player[0] == 0:
        moves.remove('UP')
    if player[0] == 2:
        moves.remove('DOWN')    


    return moves


monster, door, start = get_locations()

while True:
    moves = get_moves(player)
    print("Welcome to The Dungeon")
    print("You are currently in room {}".format(player))
    print("You can move {}".format(moves))
    print("Enter QUIT to quit")


    move = input("> ")
    move = move.upper()

    if move == QUIT:
        break

    if move in moves:
        player = move_player(player, moves)

    else:
        print("** Stop walking into walls**")
        continue 

    if player == door:
        print("You've escaped")
        break

    if player == monster:
        print("You were eaten")
        break