redef fun remove_at(i)
	do
		var node = get_node(i)
		if node != null then remove_node(node)
	end

	redef fun remove_at(index)
	do
		var node = node_at(index)
		index = index_within_node + node.head_index

		# Shift left all the elements after `index`
		for i in [index+1 .. node.tail_index[ do
			node.items[i-1] = node.items[i]
		end
		node.tail_index -= 1
		node.items[node.tail_index] = null

		length -= 1

		var next_node = node.next
		var prev_node = node.prev
		if node.is_empty and (next_node != null or prev_node != null) then
			# Empty and non-head or tail node, delete
			if next_node != null then
				next_node.prev = node.prev
			else tail_node = prev_node.as(not null)

			if prev_node != null then
				prev_node.next = node.next
			else head_node = next_node.as(not null)
		end
	end

	redef fun remove_at(ind) do
		var el = entities[ind]
		entities.remove_at(ind)
		el.set_parent null
	end

	redef fun remove_at(i)
	do
		var l = length
		if i >= 0 and i < l then
			var j = i + 1
			while j < l do
				self[j-1] = self[j]
				j += 1
			end
			_length = l - 1
		end
	end

	redef fun remove_at(index)
	do
		mutex.lock
		real_collection.remove_at(index)
		mutex.unlock
	end

	redef fun remove_at(index)
	do
		mutex.lock
		super
		mutex.unlock
	end