code: def get_viz(self, force=False):
          
          slice_params = json.loads(self.params)
          slice_params['slice_id'] = self.id
          slice_params['json'] = 'false'
          slice_params['slice_name'] = self.slice_name
          slice_params['viz_type'] = self.viz_type if self.viz_type else 'table'
  
          return viz_types[slice_params.get('viz_type')](
              self.datasource,
              form_data=slice_params,
              force=force,
          )
docs: Creates :py:class:viz.BaseViz object from the url_params_multidict.
  
          :return: object of the 'viz_type' type that is taken from the
              url_params_multidict or self.params.
          :rtype: :py:class:viz.BaseViz