text: # -*- coding: utf-8 -*-
  """
  Created on Thu Mar 25 18:26:14 2021
  
  @author: Emmanuel
  """
  
  board = {(x-3, y-3, x-y) for x in range(7) for y in range(7) if abs(x-y) <=3}
  
  def neighbors_1(x, y, z):
      res = set()
      for i in [-1, 1]:
          res.update({(x, y-i, z+i), (x+i, y+i, z), (x+i, y, z+i)})
      return {box for box in res if box in board}
      
      
  def neighbors_2(x, y, z):
      res = set()
      for a, b, c in neighbors_1(x, y, z):
          res.update(neighbors_1(a, b, c))
      res.discard((x, y, z))
      return {box for box in res if box in board}