code: def on_batch_begin(self, train, **kwargs):
          "Multiply the current lr if necessary."
          if not self.learn.gan_trainer.gen_mode and train: self.learn.opt.lr *= self.mult_lf on_batch_begin(self, train, **kwargs):
          "Multiply the current lr if necessary."
          if not self.learn.gan_trainer.gen_mode and train: self.learn.opt.lr *= self.mult_lr
docs: Multiply the current lr if necessary.