code: func (req *Request) AddPeersQuery(invocationChain ...*discovery.ChaincodeCall) *Request {
  	ch := req.lastChannel
  	q := &discovery.Query_PeerQuery{
  		PeerQuery: &discovery.PeerMembershipQuery{
  			Filter: &discovery.ChaincodeInterest{
  				Chaincodes: invocationChain,
  			},
  		},
  	}
  	req.Queries = append(req.Queries, &discovery.Query{
  		Channel: ch,
  		Query:   q,
  	})
  	var ic InvocationChain
  	if len(invocationChain) > 0 {
  		ic = InvocationChain(invocationChain)
  	}
  	req.addChaincodeQueryMapping([]InvocationChain{ic})
  	req.addQueryMapping(discovery.PeerMembershipQueryType, channnelAndInvocationChain(ch, ic))
  	return req
  }
docs: // AddPeersQuery adds to the request a peer query