q_how_to_compile.go

    var prediction Prediction
    get_resp := elasticsearch.Get(index, key)

    if(get_resp == nil) {
      prediction = Prediction {EventId: eventId, UserId: userid} 
    } else {
      json.Unmarshal(*get_resp.Source, &prediction) 
    }
    
    //cannot convert nil to type elasticsearch.ElasticGetResponse