+/**
+ * aga_bfs - Breadth-first search
+ * @_n: pointer to current node (output)
+ * @_g: graph to search
+ * @_start: node to start from
+ *
+ * Performs a breadth first search. The block following this macro is
+ * executed with @_n set first to @_start, then to each node reachable
+ * from @_start in depth first search order.
+ *
+ * aga_bfs_start() must be called before this macro is used.
+ */