Returning multiple values

Hi,

I have written an AggregateFactory Vertica UDF which returns a single value

getReturnTypes(si,columnTypes args,columnTypes returnTypes){

 returnTypes.addVarbinary(512);
 //I want to add second returnType
returnTypes.addFloat("");
} 

getProtoType(si,columnTypes args,columnTypes returnTypes){
returnTypes.addVarbinary(512);
 //I want to add second returnType
returnTypes.addFloat("");
}

this is not working, how can I return two values from an AggregateFactory UDF?