# Flatten `self` and its subsection in a `Map` of keys => values
	#
	# Properties from section are prefixed with their section names with the
	# dot (`.`) notation.
	#
	# ~~~
	# var ini = new IniFile.from_string("""
	# key=value1
	# [section]
	# key=value2
	# """)
	# assert ini.flatten.join(", ", ": ") == "key: value1, section.key: value2"
	# ~~~
	fun flatten: Map[String, String] do
		var map = new HashMap[String, String]
		for key, value in self do
			if value == null then continue
			map[key] = value
		end
		for section in sections do
			for key, value in section do
				if value == null then continue
				map["{section.name}.{key}"] = value
			end
		end
		return map
	end