code: def test_custom_unk(self):
      vocab_list = ["a", "UNK", "b", "c", "d"]
      vocab = ScriptVocabulary(vocab_list, unk_idx=1)
      self.assertEqual(
          [0, 1, 3, 4], vocab.lookup_indices_1d(["a", "e", "c", "d"])
      )
  
file_path: pytext/pytext/torchscript/tests/test_vocab.py
imports: import unittest
  import torch
  from pytext.torchscript.vocab import ScriptVocabulary
  from torch import jit
label_desc: Use image node_id 6 for calling the VocabTest obj's underlying member method code with example usage: obj.test_custom_unk() without return types