This is a little confusing since you expect that what's in the boiler plate here is suppose to be in the solution

Boiler Plate for Question

class Solution:
  def traverse(self, root):
    deq = deque()
    # TODO: Write your code here

    result = [list(sublist) for sublist in deq]
    return result

Solution - FOLLOWS SIMILAR FORMAT AS 'LEVEL ORDER TRAVERSAL' QUESTION

def traverse(root):
  result = deque()
  if root is None:
    return result

  queue = deque()
  queue.append(root)
  while queue:
    levelSize = len(queue)
    currentLevel = []
    for _ in range(levelSize):
      currentNode = queue.popleft()
      # add the node to the current level
      currentLevel.append(currentNode.val)
      # insert the children of current node in the queue
      if currentNode.left:
        queue.append(currentNode.left)
      if currentNode.right:
        queue.append(currentNode.right)

    result.appendleft(currentLevel)

  return result