code: def count_words(file):
    
    c = Counter()
    with open(file, 'r') as f:
      for l in f:
        words = l.strip().split()
        c.update(words)
    return c
docs: Counts the word frequences in a list of sentences.
  
    Note:
      This is a helper function for parallel execution of `Vocabulary.from_text`
      method.