code: def on_step_end(self, step, logs={}):
          
          self.total_steps += 1
          if self.total_steps % self.interval != 0:
              # Nothing to do.
              return
  
          filepath = self.filepath.format(step=self.total_steps, **logs)
          if self.verbose > 0:
              print('Step {}: saving model to {}'.format(self.total_steps, filepath))
          self.model.save_weights(filepath, overwrite=True)
docs: Save weights at interval steps during training