"Static Local Function Example"

public string CreateUserDetailsString(string additionalData) {
	static string CombineData(string permanentData, string additionalData) {
		return permanentData + additionalData;
	}

	return $"{Name} ({CombineData(PermanentData, additionalData)})";
}


Code snippet taken from "Two Decades of C#: A Reference - C# 8".