code: def enrich_reactions(graph: BELGraph):
      
      nodes = list(get_nodes_by_function(graph, REACTION))
      for u in nodes:
          for v in u.reactants:
              graph.add_has_reactant(u, v)
  
          for v in u.products:
              graph.add_has_product(u, v)
docs: Adds all of the reactants and products of reactions to the graph.