docs: def fast_comp(seq1, seq2, transpositions=False):
  	"""Compute the distance between the two sequences `seq1` and `seq2` up to a
  	maximum of 2 included, and return it. If the edit distance between the two
  	sequences is higher than that, -1 is returned.
  	
  	If `transpositions` is `True`, transpositions will be taken into account for
  	the computation of the distance. This can make a difference, e.g.:
  
  		>>> fast_comp("abc", "bac", transpositions=False)
  		2
  		>>> fast_comp("abc", "bac", transpositions=True)
  		1
  	
  	This is faster than `levenshtein` by an order of magnitude, but on the
  	other hand is of limited use.
  
  	The algorithm comes from `http://writingarchives.sakura.ne.jp/fastcomp`.
  	I've added transpositions support to the original code.
  	"""
  	replace, insert, delete = "r", "i", "d"
  
  	L1, L2  = len(seq1), len(seq2)
  	if L1 < L2:
  		L1, L2 = L2, L1
  		seq1, seq2 = seq2, seq1
  
  	ldiff = L1 - L2
  	if ldiff == 0:
  		models = (insert+delete, delete+insert, replace+replace)
  	elif ldiff == 1:
  		models = (delete+replace, replace+delete)
  	elif ldiff == 2:
  		models = (delete+delete,)
  	else:
  		return -1
  
  	res = 3
  	for model in models:
  		i = j = c = 0
  		while (i < L1) and (j < L2):
  			if seq1[i] != seq2[j]:
  				c = c+1
  				if 2 < c:
  					break
              
  				if transpositions and ldiff != 2 \
              	and i < L1 - 1 and j < L2 - 1 \
              	and seq1[i+1] == seq2[j] and seq1[i] == seq2[j+1]:
  					i, j = i+2, j+2
  				else:
  					cmd = model[c-1]
  					if cmd == delete:
  						i = i+1
  					elif cmd == insert:
  						j = j+1
  					else:
  						assert cmd == replace
  						i,j = i+1, j+1
  			else:
  				i,j = i+1, j+1
  
  		if 2 < c:
  			continue
  		elif i < L1:
  			if L1-i <= model[c:].count(delete):
  				c = c + (L1-i)
  			else:
  				continue
  		elif j < L2:
  			if L2-j <= model[c:].count(insert):
  				c = c + (L2-j)
  			else:
  				continue
  
  		if c < res:
  			res = c
  
  	if res == 3:
  		res = -1
  	return res