bool agar_dijkstra_path(struct agar_state *sr, const void *destr,
aga_icost_t *total_cost,
const void **prevr, const void **prevedge);
bool agar_dijkstra_path(struct agar_state *sr, const void *destr,
aga_icost_t *total_cost,
const void **prevr, const void **prevedge);