Static local functions

Local functions have been introduced to make the code more readable by constraining the visibility of a certain piece of code to a single method:

void PrintName(Person person)
{
    var p = person ?? throw new ArgumentNullException(nameof(person));
    Console.WriteLine(Obfuscated());
    string Obfuscated()
    {
        if (p.Age < 18) return $"{p.FirstName[0]}. {p.LastName[0]}.";
        return $"{p.FirstName} {p.LastName}"; 
    }
}

In this example, the Obfuscated method can only be used by PrintName and has the advantage of being able to ignore any parameter check, because the context where the p captured parameter is used does not allow its value to be null. This can deliver performance advantages in complex scenarios, but its ability to capture the...