Python编程把二叉树打印成多行代码

class TreeNode(): 
  def __init__(self,x): 
    self.val = x 
    self.left = None 
    self.right = None 
def function(root): 
  result = [] 
  if not root: 
    return result 
  A = [] 
  A.append(root) 
  while A: 
    temp = [] 
    size = len(A) 
    for Node in A: 
      temp.append(Node.val) 
    result.append(temp) 
    for i in range(size): 
      node = A.pop(0) 
      if node.left: 
        A.append(node.left) 
      if node.right: 
        A.append(node.right) 
  return result