c# thread safe extension method

public static class ExtensionMethod {
	public static TResult SafeInvoke(this T isi, Func call) where T : ISynchronizeInvoke {
		if(isi.InvokeRequired) {
			IAsyncResult result = isi.BeginInvoke(call, new object[] { isi });
			object endResult = isi.EndInvoke(result);
			return (TResult)endResult;
		} else {
			return call(isi);
		}
	}

	public static void SafeInvoke(this T isi, Action call) where T : ISynchronizeInvoke {
		if(isi.InvokeRequired)
			isi.BeginInvoke(call, new object[] { isi });
		else
			call(isi);
	}
}