class_docstr: A data generator for a graph containing sequence data, created by sliding windows across the
  features of each node in a graph.
  
  .. seealso:: Model using this generator: :class:`.GCN_LSTM`.
  
  Args:
      G (StellarGraph): a graph instance where the node features are ordered sequence data
      window_size (int): the number of sequence points included in the sliding window.
      batch_size (int, optional): the number of sliding windows to include in each batch.
code: def num_batch_dims(self):
      return 1
  
file_path: stellargraph/stellargraph/mapper/sliding.py
imports: import numpy
  from .None import Generator
  from tensorflow.keras.utils import Sequence
  from ..core.validation import require_integer_in_range
label_desc: Use image node_id 2 for calling the SlidingFeaturesNodeGenerator obj's underlying member method code with example usage: obj.num_batch_dims() and returns: int