comefrom: <doocs>1740.Find Distance in a Binary Tree_1.py
code: def dfs(root, v):
      if root is None:
          return -1
      if root.val == v:
          return 0
      left, right = dfs(root.left, v), dfs(root.right, v)
      if left == right == -1:
          return -1
      return 1 + max(left, right)
masked: def sample_funcname ( var_1 , var_2 ) :
      if var_1 is None :
          return - 1
      if var_1.val == var_2 :
          return 0
      left , right = var_0 ( var_1.left , var_2 ) , var_0 ( var_1.right , var_2 )
      if left == right == - 1 :
          return - 1
      return 1 + max ( left , right )
  