class_docstr: A `Dataset` that groups its input and performs a windowed reduction.
code: def element_spec(self):
      return self._element_spec
  
file_path: tensorflow/tensorflow/python/data/ops/group_by_window_op.py
imports: from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.data.ops import structured_function
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_spec
  from tensorflow.python.ops import gen_experimental_dataset_ops
label_desc: Use image node_id 5 for calling the _GroupByWindowDataset obj's underlying member method code with example usage: obj.element_spec() and returns: self