# Sort an array through a `for` abuse.
	# The user uses the provided query (item) to implements its own comparison
	#
	#     var a = [1, 3, 2]
	#     for q in a.sort_fa do q.res = q.a <=> q.b
	#     assert a ==  [1, 2, 3]
	#
	# Implements a sort by permutation.
	fun sort_fa: ForAbuser[CompareQuery[E]]
	do
		return new SortAbuser[E](self)
	end