'Called when an epoch is about to end
Arguments:
callback_data (HDF5 dataset): shared data between callbacks
model (Model): model object
epoch (int): index of epoch that is ending'

def on_epoch_end(self, callback_data, model, epoch):

    if (self.history > 1):
        self.save_history(epoch, model)
    else:
        save_obj(model.serialize(keep_states=True), self.save_path)
