code: def _assemble_conversion(self, stmt):
          
          pybel_lists = ([], [])
          for pybel_list, agent_list in \
                              zip(pybel_lists, (stmt.obj_from, stmt.obj_to)):
              for agent in agent_list:
                  node = _get_agent_grounding(agent)
                  # TODO check for missing grounding?
                  pybel_list.append(node)
  
          rxn_node_data = reaction(
              reactants=pybel_lists[0],
              products=pybel_lists[1],
          )
          obj_node = self.model.add_node_from_data(rxn_node_data)
          obj_edge = None  # TODO: Any edge information possible here?
          # Add node for controller, if there is one
          if stmt.subj is not None:
              subj_attr, subj_edge = _get_agent_node(stmt.subj)
              subj_node = self.model.add_node_from_data(subj_attr)
              edge_data_list = _combine_edge_data(pc.DIRECTLY_INCREASES,
                                             subj_edge, obj_edge, stmt.evidence)
              for edge_data in edge_data_list:
                  self.model.add_edge(subj_node, obj_node, **edge_data)
docs: Example: p(HGNC:HK1) => rxn(reactants(a(CHEBI:"CHEBI:17634")),
                                         products(a(CHEBI:"CHEBI:4170")))