text: GNN_MSG_KEY = 'm'
  GNN_NODE_FEAT_IN_KEY = 'hn_in'
  GNN_NODE_FEAT_OUT_KEY = 'hn_out'
  GNN_EDGE_FEAT_KEY = 'he'
  GNN_AGG_MSG_KEY = 'h_msg'
  GNN_NODE_NORM = 'norm'
  GNN_NODE_LABELS_KEY = 'hnl'
  GNN_NODE_ATTS_KEY = 'hna'
  GNN_EDGE_LABELS_KEY = 'hel'
  GNN_EDGE_NORM = 'norm'
  
  GRAPH_CLASSIFICATION = 'graph_classification'
  NODE_CLASSIFICATION = 'node_classification'
  
  AIFB = 'aifb'
  MUTAG = 'mutag'
  MUTAGENICITY = 'mutagenicity'
  PTC_FM = 'ptc_fm'
  PTC_FR = 'ptc_fr'
  PTC_MM = 'ptc_mm'
  PTC_MR = 'ptc_mr'
  
  