using System;

public static class Extensions

{

    public static T ThrowIf<T, TException>(this T instance, Func<T, bool> check, Func<TException> exceptionFactory) where TException : Exception => !check(instance) ? instance : throw exceptionFactory();

}

​

public class Program

{

    public static void Main()

    {

        int number = -5;

​

        number.ThrowIf(n => n < 0, () => new ArgumentException("Number cannot be negative"));

    }

}