code: func (s *Simulation) AddNodesAndConnectChain(count int, opts ...AddNodeOption) (ids []enode.ID, err error) {
  	if count < 2 {
  		return nil, errors.New("count of nodes must be at least 2")
  	}
  	id, err := s.AddNode(opts...)
  	if err != nil {
  		return nil, err
  	}
  	err = s.Net.ConnectToLastNode(id)
  	if err != nil {
  		return nil, err
  	}
  	ids, err = s.AddNodes(count-1, opts...)
  	if err != nil {
  		return nil, err
  	}
  	ids = append([]enode.ID{id}, ids...)
  	err = s.Net.ConnectNodesChain(ids)
  	if err != nil {
  		return nil, err
  	}
  	return ids, nil
  }
docs: // AddNodesAndConnectChain is a helpper method that combines
  // AddNodes and ConnectNodesChain. The chain will be continued from the last
  // added node, if there is one in simulation using ConnectToLastNode method.