input: Write a python function to count the number of empty spaces (MAZE_EMPTY) in the maze.
  assert count_empty_spaces(maze) == 114
  assert count_empty_spaces([[0, 2], [1, 1]]) == 2
  assert count_empty_spaces([[0, 0], [0, 0]]) == 0
output: def count_empty_spaces(maze):
      MAZE_EMPTY = 1
      return sum(row.count(MAZE_EMPTY) for row in maze)