/// <summary>
 /// Marks this tensor to be watched by the given tape.
 /// </summary>
 /// <param name="x"></param>
 public void watch(Tensor x)
 {
     _tape.watch(x as EagerTensor);
 }
 /// <summary>
 /// Marks this tensor to be watched by the given tape.
 /// </summary>
 /// <param name="x"></param>
 public void watch(Tensor x)
 {
     _tape.watch(x);
 }