# Filter: reject the last `length` items.
	#
	#     assert [1,2,3,4,5].iterator.skip_tail(2).to_a	     ==  [1,2,3]
	#
	# Important: require O(length) in memory
	fun skip_tail(length: Int): Iterator[E]
	do
		return new PipeSkipTail[E](self, length)
	end