I am trying to use webservice in Dynamics AX2012

When trying to use GetPrice method it is asking for "AuthenticationTicketHeader" in first argument. How do I get value of AuthenticationTicketHeader? What is the datatype of authenticationTicketHeader?

below is the code in X++

  #define.UserId("distar")
    #define.Pass("grothman")
   
    ClrObject clientType;   
    RapImportService.HOF_RapPriceService.RapaportPricesSoapClient _client;
   
    real price;
  

    ;
   
    clientType = CLRInterop::getType("RapImportService.HOF_RapPriceService.RapaportPricesSoapClient");   
    _client   = AifUtil::createServiceClient(clientType);  
    _client.Login(#UserId,#Pass);

 // here it will ask for "AuthenticationTicketHeader" as first argument   
    price = _client.GetPrice(AuthenticationTicketHeader,shape,size,color,clarity)