docs: def _get_wms_request(self, bbox, size_x, size_y):
          """
          Returns WMS request.
          """
          bbox_3857 = transform_bbox(bbox, CRS.POP_WEB)
  
          return GeopediaWmsRequest(layer=self.layer,
                                    theme=self.theme,
                                    bbox=bbox_3857,
                                    width=size_x,
                                    height=size_y,
                                    image_format=self.image_format,
                                    custom_url_params={CustomUrlParam.TRANSPARENT: True})