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 coordinates, or None if no valid path is found.
  
  
  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), (4, 2)) == [[(4, 2)]]
  assert find_path((4, 2), (4, 3)) == [[(4, 2)], [(4, 3)]]
  assert find_path((4, 2), (9, 9)) == [[(4, 2)], [(5, 2)], [(6, 2)], [(7, 2)], [(8, 2)], [(9, 2)], [(9, 3)], [(9, 4)], [(9, 5)], [(9, 6)], [(9, 7)], [(9, 8)], [(9, 9)]]
  assert find_path((4, 2), (1, 1)) == None
  assert find_path((0, 0), (1, 1)) == [[(0, 0)], [(1, 0)], [(1, 1)]]
  
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 tuple(position) not in visited and max_tries > 0:
              visited.add(tuple(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