I don’t understand why I have put it out of the if-else statement:
1/ If the model is not load (case Else: ) then the trainer.add_event_handler(Events.ITERATION_STARTED, lr_scheduler)
is execute
2/ if the model was load, then it should load the lr_scheduler too
 to_save = {'trainer': trainer, 'model': model, 'optimizer': optimizer, 'lr_scheduler': lr_scheduler}
and
to_load = {'trainer': trainer, 'model': model, 'optimizer': optimizer, 'lr_scheduler': lr_scheduler}