DisposableMe.cs

class DisposableMe : IDisposable
{
    private bool _disposed = false;

    // 1. field that implements IDisposable
    // 2. field that stores "native resource" (ex: IntPtr)

    ~DisposableMe()
    {
        Cleanup("called from GC" != null);
    }           // = true

    public void Dispose()
    {
        Cleanup("not from GC" == null);
    }           // = false
    
    ...
}