message: Fix typo in eager value_and_gradients docstring
diff: @@ -550,7 +550,7 @@ def _ensure_unique_tensor_objects(parameter_positions, args):
  def val_and_grad_function(f, params=None):
  - """Returns a function that computes f and is derivative w.r.t. params.
  + """Returns a function that computes f and its derivative w.r.t. params.
  Example:
  ```python
  