comefrom: <doocs>0530.Minimum Absolute Difference in BST_1.py
code: def dfs(root):
      if root is None:
          return
      dfs(root.left)
      nonlocal ans, prev
      ans = min(ans, abs(prev - root.val))
      prev = root.val
      dfs(root.right)
masked: def sample_funcname ( var_1 ) :
      if var_1 is None :
          return
      var_0 ( var_1.left )
      nonlocal var_4 , var_5
      var_4 = min ( var_4 , abs ( var_5 - var_1.val ) )
      var_5 = var_1.val
      var_0 ( var_1.right )
  