+/*
+ * Define AS_STATS for A* statistics on stderr.
+ *
+ * Define AS_NO_PATH_CACHE to disable the path cache. The path cache
+ * saves a lot of work, but uses lots of memory. It should be a
+ * significant net win, unless you run out of memory.
+ *
+ * Define AS_NO_NEIGHBOR_CACHE to disable the neighbor cache. The
+ * neighbor cache trades a modest amount of memory to save a bit of
+ * work. In its current form, it doesn't really make a difference.
+ */
+