extern VikDataSourceInterface vik_datasource_gps_interface;
extern VikDataSourceInterface vik_datasource_google_interface;
extern VikDataSourceInterface vik_datasource_gc_interface;
extern VikDataSourceInterface vik_datasource_gps_interface;
extern VikDataSourceInterface vik_datasource_google_interface;
extern VikDataSourceInterface vik_datasource_gc_interface;