code: def get_next_step(self):
          
          layer_mode = self.parent.step_kw_layermode.selected_layermode()
          if layer_mode == layer_mode_classified:
              new_step = self.parent.step_kw_classify
          elif layer_mode == layer_mode_continuous:
              new_step = self.parent.step_kw_threshold
          else:
              message = tr('Layer mode should be continuous or classified')
              raise InvalidWizardStep(message)
          return new_step
docs: Find the proper step when user clicks the Next button.
  
          :returns: The step to be switched to
          :rtype: WizardStep instance or None