# Return an unique and stable identifier associated with an escapemark
	fun escapemark_name(e: nullable EscapeMark): String
	do
		assert e != null
		if frame.escapemark_names.has_key(e) then return frame.escapemark_names[e]
		var name = e.name
		if name == null then name = "label"
		name = get_name(name)
		frame.escapemark_names[e] = name
		return name
	end