def highlightSubsequence(sequence, x1, x2, start=' [', stop = '] ') :
	"""returns a sequence where the subsequence in [x1, x2[ is placed 
	in bewteen 'start' and 'stop'"""

	seq = list(sequence)
	print(x1, x2-1, len(seq))
	seq[x1] = start + seq[x1]
	seq[x2-1] = seq[x2-1] + stop
	return ''.join(seq)