_lanes = {}
_stacks = {}
_last_name = {}
_being_towed = {}

_reset_last_name(block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _last_name
		remove(_last_name, block_type)


_set_last_name(name, block_type=null)
	if block_type == null
		block_type = called-from[1]

	_last_name[block_type] = name

_get_last_name(block_type)
	if block_type == null
		block_type = called-from[1]

	if block_type in _last_name
		return _last_name[block_type]
	else 
		return null

_current_block_type()
	return called-from[1]

_call_stack_till_first(block_type)
	striped = slice(called-from, 2)
	block_index = (index(striped, block_type))
	if block_index == null
		if length(striped) <= 1
			return (striped ())
		return slice(striped, 1)
	stack = ()
	for i in (0..block_index)
		push(stack, striped[i])
	return stack


_push_onto_stack(block, block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _stacks
		stack = _stacks[block_type]
	else
		stack = ()
	
	push(stack, block)
	_stacks[block_type] = stack

_pop_from_stack(block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _stacks
		stack = _stacks[block_type]
		b = pop(stack)
		if length(stack) > 0
			_stacks[block_type]
		else 
			remove(_stacks, block_type)
		return b
	return null

_pop_stack(block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _stacks
		stack = _stacks[block_type]
		remove(_stacks, block_type)
		return stack
	else
		return ()

_add_to_lane(key, value, block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _lanes
		lane = _lanes[block_type]
	else
		lane = {}

	if key in lane
		stack = lane[key]
	else
		stack = ()

	push(stack, value)
	lane[key] = stack
	_lanes[block_type] = lane

_put_into_lane(key, value, block_type=null)
	if block_type == null
		block_type = called-from[1]

	if block_type in _lanes
		lane = _lanes[block_type]
	else
		lane = {}
	
	lane[key] = value
	_lanes[block_type] = lane

_pop_lane(block_type=null)
	if block_type == null
		block_type = called-from[1]
	
	if block_type in _lanes
		lane = _lanes[block_type]
		remove(_lanes, block_type)
		return lane
	else
		return {}

attach(parent_type, suffix, block)
	_being_towed[_current_block_type()] = true
	call_stack = _call_stack_till_first(parent_type)
	if parent_type in call_stack
		// We are called inside a block
		_push_onto_stack(block)
		//Detect if the selector will be generated
		//by an earlier call of RV-Element
		if not _current_block_type() in (call_stack)
			block_list = _pop_stack()
			_put_into_lane(suffix, block_list, parent_type)
	else
		// We are not called inside a block
		// Is there a block to attach to
		_last_parent_name = _get_last_name(parent_type)
		if _last_parent_name != null
			& .{_last_parent_name} .{_last_parent_name}{suffix}
				{block}

tow(name, block, block_type=null)
	if block_type == null	// Determining if we are inside a block or after a block
		block_type = called-from[0]

	.{name}
		{block}
		if block_type in _lanes
			for suffix, block_list in _pop_lane(block_type)
				p(name suffix selector())
				&{name}{suffix}
					for current_block in block_list
						{current_block}

	_set_last_name(name, block_type)