message: Add example code to tf.data.Dataset.filter() documentation
diff: @@ -1100,6 +1100,21 @@ class DatasetV2(object):
  def filter(self, predicate):
  """Filters this dataset according to `predicate`.
  + ```python
  + # NOTE: The following examples use `{ ... }` to represent the
  + # contents of a dataset.
  + a = { 1, 2, 3 }
  + b = { 4, 5, 6, 7 }
  +
  + a.filter(lambda x: x < 3) == { 1, 2 }
  +
  + # `tf.math.equal(x, y)` is required for equality comparison
  + def filter_fn(x):
  + return tf.math.equal(x, 4)
  +
  + b.filter(filter_fn) == { 4 }
  + ```
  +
  Args:
  predicate: A function mapping a nested structure of tensors (having shapes
  and types defined by `self.output_shapes` and `self.output_types`) to a
  