public void DoSomething(string parameter) { if (CheckNotNull(parameter, "parameter")) { // Perform some action with the parameter } } public bool CheckNotNullIn this example, the `DoSomething` method checks if the `parameter` value is not null using the `CheckNotNull` method. If the parameter is not null, the method performs some action with the parameter. If the parameter is null, the CheckNotNull method throws an `ArgumentNullException`. The CheckNotNull method is commonly used in the .NET framework and can be found in the System.Runtime.CompilerServices namespace. However, it is also commonly used in third-party libraries and packages for defensive programming.(T value, string paramName) where T : class { if (value == null) { throw new ArgumentNullException(paramName); } return true; }