def fetch
        response = client.fetch_object(parse_class, id)
        return nil if response.error?
        response.result
      end
def fetch
        response = client.fetch_object(parse_class, id)
        return nil if response.error?
        response.result
      end
This method is a general implementation that gets overriden by Parse::Object subclass.
 Given the class name and the id, we will go to Parse and fetch the actual record, returning the
 JSON object.
 @return [Parse::Object] the fetched Parse::Object, nil otherwise.