code: def __matches(s1, s2, ngrams_fn, n=3):
      
      ngrams1, ngrams2 = set(ngrams_fn(s1, n=n)), set(ngrams_fn(s2, n=n))
      return ngrams1.intersection(ngrams2)
docs: Returns the n-grams that match between two sequences
  
          See also: SequenceMatcher.get_matching_blocks
  
          Args:
              s1: a string
              s2: another string
              n: an int for the n in n-gram
  
          Returns:
              set: