# Process the mardown `input` string and return the processed output.
	fun process(input: String): Writable do
		# init processor
		link_refs.clear
		last_link_ref = null
		current_line = null
		current_block = null
		# parse markdown
		var parent = read_lines(input)
		parent.remove_surrounding_empty_lines
		recurse(parent, false)
		# output processed text
		decorator.headlines.clear
		return emit(parent.kind)
	end