Returns WMS request.

def _get_wms_request(self, bbox, time_interval, size_x, size_y, maxcc, time_difference, custom_url_params):
        """
        Returns WMS request.
        """
        return WmsRequest(layer=self.data_feature,
                          bbox=bbox,
                          time=time_interval,
                          width=size_x,
                          height=size_y,
                          maxcc=maxcc,
                          custom_url_params=custom_url_params,
                          time_difference=time_difference,
                          image_format=self.image_format,
                          data_source=self.data_source,
                          instance_id=self.instance_id)