code: def instantiate(self, **extra_args):
          
          input_block = self.input_block.instantiate()
          backbone = self.backbone.instantiate(**extra_args)
  
          return QRainbowModel(
              input_block=input_block,
              backbone=backbone,
              action_space=extra_args['action_space'],
              vmin=self.vmin,
              vmax=self.vmax,
              atoms=self.atoms,
              initial_std_dev=self.initial_std_dev,
              factorized_noise=self.factorized_noise
          )
docs: Instantiate the model