class_docstr: Google robot pushing dataset.
code: def num_channels(self):
      return 3
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import io
  import os
  import numpy
  from tensor2tensor.data_generators import generator_utils
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import video_utils
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the VideoGoogleRobotPushing obj's underlying member method code with example usage: obj.num_channels() and returns: int