using System;

// see: https://stackoverflow.com/a/51268143/1016343

public class Program

{

    public static void Main()

    {

        CustomClass c1 = null;

        CustomClass c2 = new CustomClass();

​

        bool b1 = c1; // is false

        bool b2 = c2; // is true

​

        if (!c1 && c2)

        {

            // Do stuff

            "True".Dump();

        }

    }

}

​

public class CustomClass

{

    public static implicit operator bool(CustomClass c)

    {

        if (c == null) return false;

        else return true;

    }

}