# Returns a view on `self` macros on the form `macro.name`/`macro.replacement`.
	#
	# Given that all macros with the same name are all replaced with the same
	# replacement, this view contains only one entry for each name.
	#
	#     var tpl = new TemplateString("Hello %FIRSTNAME%, %LASTNAME%!")
	#     for name, rep in tpl do assert rep == null
	#     tpl.replace("FIRSTNAME", "Corben")
	#     tpl.replace("LASTNAME", "Dallas")
	#     for name, rep in tpl do assert rep != null
	fun iterator: MapIterator[String, nullable Writable] do
		return new TemplateStringIterator(self)
	end