anchor.diff:        'Result-Code' := ?INVALID_AVP_LENGTH,
         'Origin-Host' := _,
         'Origin-Realm' := _,
  -      'User-Name' := _,
  -      'Class' := _,
  -      'Error-Message' := _,
  -      'Error-Reporting-Host' := _,
         'Failed-AVP' := Avps}
           = call(Config, Req),
       [[_]] = failed_avps(Avps, Config).
  
positive.code:     ApplId = app(Req, Name, Dict0),
      #diameter_header{application_id = ApplId} = H,  %% assert
      Dict = dict(Ans, Dict0),
      [R | Vs] = Dict:'#get-'(answer(Ans, Es, Name)),
      maps:put(':name',
               Dict:rec2msg(R),
               maps:from_list([T || {_,V} = T <- Vs,
                                    V /= undefined,
                                    V /= []])).
  
  %% Missing Result-Code and inappropriate Experimental-Result-Code.
  answer(Rec, Es, send_experimental_result) ->
  
negative.code:     find(Group, Peers).
  
  find(#group{client_service = CN,
              server_decoding = D,
              server_encoding = E,
              server_container = C},
       [_|_] = Peers) ->
      Id = {D,E,C},
      [P] = [P || P <- Peers, id(Id, P, CN)],
      {ok, P}.
  
  