C# 7 - Return reference - https://codingblast.com/csharp-7-return-reference-local-reference/

ReferenceReturn.cs

public class RefReturns
{
    public RefReturns()
    {
        this._grade = 2;
    }

    private int _grade;

    public void PrintGrade()
    {
        Console.WriteLine($"Grade: {this._grade}");
    }

    public ref int DoStuff()
    {
        return ref this._grade;
    }
}


class Program
{
    static void Main(string[] args)
    {
        RefReturns refReturns = new RefReturns();

        ref int grade = ref refReturns.DoStuff();

        grade = 17;

        refReturns.PrintGrade();
    }
}