message: Update usage example as per review suggestions
diff: @@ -983,13 +983,9 @@ def is_tensor(x): # pylint: disable=invalid-name
  can be converted to a tensor using `ops.convert_to_tensor(x)`.
  Usage example:
  - >>> x = tf.constant([[1,2,3],[4,5,6],[7,8,9]])
  - >>> print(x.shape)
  - (3, 3)
  - >>> print(tf.is_tensor(x))
  + >>> tf.is_tensor(constant([[1,2,3],[4,5,6],[7,8,9]]))
  True
  - >>> y = "Hello World"
  - >>> print(tf.is_tensor(y))
  + >>> tf.is_tensor("Hello World"))
  False
  Args:
  