class_docstr: Manages placeholders associated with batch of graphs and their topology
code: def get_deg_slice_placeholder(self):
      return self.deg_slice_placeholder
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import unicode_literals
  import warnings
  import numpy
  import tensorflow
  from deepchem.nn.copy import Input
  from deepchem.feat.mol_graphs import ConvMol
label_desc: Use image node_id 6 for calling the GraphTopology obj's underlying member method code with example usage: obj.get_deg_slice_placeholder() and returns: self