code: def from_vocabfile(filename):
      
      word_count = [x.strip().split() for x in _open(filename, 'r').read().splitlines()]
      word_count = {w:int(c) for w,c in word_count}
      return CountedVocabulary(word_count=word_count)
docs: Construct a CountedVocabulary out of a vocabulary file.
  
      Note:
        File has the following format word1 count1
                                      word2 count2