code: def get_next_step(self):
          
          subcategory = self.parent.step_kw_subcategory.selected_subcategory()
          is_raster = is_raster_layer(self.parent.layer)
          has_classifications = get_classifications(subcategory['key'])
  
          # Vector
          if not is_raster:
              return self.parent.step_kw_field
          # Raster and has classifications
          elif has_classifications:
              return self.parent.step_kw_multi_classifications
          # else go to source
          return self.parent.step_kw_source
docs: Find the proper step when user clicks the Next button.
  
          :returns: The step to be switched to.
          :rtype: WizardStep instance or None