struct ConfigKey{
	std::string doc;
	std::string key;
};

std::map< ConfigKey, std::string > m = parse<>(
	"(
		(= foo opt =)
		foo = 1

		(= bar opt =)
		bar = 2
	)";

m = { {{"foo opt", "foo"}, "1"}, {{"bar opt", "bar"}, "2"} }