code: def get_causal_central_nodes(graph: BELGraph, func: str) -> Set[BaseEntity]:
      
      return {
          node
          for node in graph
          if node.function == func and is_causal_central(graph, node)
      }
docs: Return a set of all nodes that have both an in-degree > 0 and out-degree > 0.
  
      This means that they are an integral part of a pathway, since they are both produced and consumed.