code: def _describe_fields(cls):
          
          dispatch_table = {
              'ShortestPathModel': 'sssp',
              'GraphColoringModel': 'graph_coloring',
              'PagerankModel': 'pagerank',
              'ConnectedComponentsModel': 'connected_components',
              'TriangleCountingModel': 'triangle_counting',
              'KcoreModel': 'kcore',
              'DegreeCountingModel': 'degree_count',
              'LabelPropagationModel': 'label_propagation'
          }
          try:
              toolkit_name = dispatch_table[cls.__name__]
              toolkit = _tc.extensions._toolkits.graph.__dict__[toolkit_name]
              return toolkit.get_model_fields({})
          except:
              raise RuntimeError('Model %s does not have fields description' % cls.__name__)
docs: Return a dictionary for the class fields description.
          Fields should NOT be wrapped by _precomputed_field, if necessary