input: Write a function to find the most efficient path for a robot to take from its current location to the destination. The function should return the path as a list of positions taken from start to end. If no path is found, return None.
  
  def find_path(start, end):
      x = start[0]
      y = start[1]
      goal_x = end[0]
      goal_y = end[1]
      visited = set()
      queue = [([x, y], [])]
      neighbor = [[1, 0], [0, 1], [-1, 0], [0, -1]]
      max_tries = 100
      while queue:
          position, path = queue.pop(0)
          if position[0] == goal_x and position[1] == goal_y:
              return path + [position]
          if position not in visited and max_tries > 0:
              visited.add(position)
              max_tries = max_tries - 1
              for neighbor_x, neighbor_y in neighbor:
                  next_x = position[0] + neighbor_x
                  next_y = position[1] + neighbor_y
                  queue.append(([next_x, next_y], path + [position]))
      return None
  
  assert find_path((4, 2), (9, 9))==[([4, 2], []), ([5, 2], [4, 2]), ([6, 2], [5, 2])]
  assert find_path((1, 1), (3, 3))==[([1, 1], []), ([2, 1], [1, 1]), ([3, 1], [2, 1]), ([3, 2], [3, 1]), ([3, 3], [3, 2])]
  assert find_path((0, 0), (2, 2))==[([0, 0], []), ([1, 0], [0, 0]), ([2, 0], [1, 0]), ([2, 1], [2, 0]), ([2, 2], [2, 1])]
  assert find_path((0, 0), (2, 3))==None
  assert find_path((5, 5), (5, 5))==[([5, 5], [])]
output: def find_path(start, end):
      x = start[0]
      y = start[1]
      goal_x = end[0]
      goal_y = end[1]
      visited = set()
      queue = [([x, y], [])]
      neighbor = [[1, 0], [0, 1], [-1, 0], [0, -1]]
      max_tries = 100
      while queue:
          position, path = queue.pop(0)
          if position[0] == goal_x and position[1] == goal_y:
              return path + [position]
          if position not in visited and max_tries > 0:
              visited.add(position)
              max_tries = max_tries - 1
              for neighbor_x, neighbor_y in neighbor:
                  next_x = position[0] + neighbor_x
                  next_y = position[1] + neighbor_y
                  queue.append(([next_x, next_y], path + [position]))
      return None