code: public void ser(Object datum, OutputStream output) throws IOException {
  		Map<Class, Serializer> serializers = cachedSerializers.get();
  		Serializer ser = serializers.get(datum.getClass());
  		if(ser == null) {
  			ser = serialization.getSerializer(datum.getClass());
  			if(ser == null) {
  				throw new IOException("Serializer for class " + datum.getClass() + " not found");
  			}
  			serializers.put(datum.getClass(), ser);
  		}
  		ser.open(output);
  		ser.serialize(datum);
  		ser.close();
  	}
docs: Serializes the given object using the Hadoop serialization system.