code: def test_optional_nested(self):
      def optional_nested(x: Any):
          assert torch.jit.isinstance(x, Optional[List[str]])
  
      x = ["a", "b", "c"]
      self.checkScript(optional_nested, (x,))
  
imports: import os
  import sys
  import torch
  import warnings
  from typing import List, Any, Dict, Tuple, Optional
  from torch.testing._internal.jit_utils import JitTestCase
label_desc: Use image node_id 15 for calling the TestIsinstance obj's underlying member method code with example usage: obj.test_optional_nested() without return types