Substring(S):
	last = ""
	array = []

	if(head(S).empty())
		ret array;

	if(last.empty())
		last = head(S)

	else if(last == head(S))
		last = last +head(S)
	else if(lsat != head(S))
		array.append(last)
		last = ""

	Substring(S)