_Fold[list,index,current,worker:out]
{
	newval <- [worker]Call[current, [list]Index[index], index]
	
	[list]Next[index]
	{
		out <- _Fold[list, ~, newval, worker]
	}{
		out <- Val[newval]
	}
}

Fold[worker,start,list:out]
{
	[list]First
	{
		out <- _Fold[list, ~, start, worker]
	}{
		out <- start
	}
}