code: def sorensen(seq1, seq2):
  	
  	set1, set2 = set(seq1), set(seq2)
  	return 1 - (2 * len(set1 & set2) / float(len(set1) + len(set2)))
docs: Compute the Sorensen distance between the two sequences `seq1` and `seq2`.
  	They should contain hashable items.
  	
  	The return value is a float between 0 and 1, where 0 means equal, and 1 totally different.