code: def test_ngram_tokenizer():
      inputs = "Hello, I'm a single sentence!"
      tokenizer = NgramTokenizer(n=2)
      tokens_expected = [
          "Hello,",
          "I'm",
          "a",
          "single",
          "sentence!",
          "Hello, I'm",
          "I'm a",
          "a single",
          "single sentence!",
      ]
      tokens = tokenizer(inputs)
      assert tokens == tokens_expected
  
file_path: ludwig/tests/ludwig/utils/test_tokenizers.py
imports: import os
  import pytest
  import torch
  import torchtext
  from ludwig.utils.tokenizers import EnglishLemmatizeFilterTokenizer, NgramTokenizer, StringSplitTokenizer
label_desc: Use image node_id 2 for calling a global function with example usage: test_ngram_tokenizer() without return types