code: def test_count_tokens():
      data = ["a b c", "c d e"]
      raw_vocab = count_tokens(data)
      assert raw_vocab == Counter(
          {"a": 1, "b": 1, "c": 2, "d": 1, "e": 1}
      )
  
file_path: sockeye/test/unit/test_vocab.py
imports: import pytest
  from unittest import mock
  from collections import Counter
  import sockeye.constants
  from sockeye.vocab import build_vocab, get_ordered_tokens_from_vocab, is_valid_vocab, _get_sorted_source_vocab_fnames, count_tokens
label_desc: Use image node_id 1 for calling a global function with example usage: test_count_tokens() without return types