#define STATE_NOTFOUND -1 // 'Not found" state of treasures */
#define STATE_GROUND 0 // After discovered, before messed with
+/* Map a state property value to a negative range, where the object cannot be
+ * picked up but the value can be recovered later. Avoid colliding with -1,
+ * which has its own meaning. */
+#define STASHED(obj) (-1 - game.prop[obj])
+
/*
* MOD(N,M) = Arithmetic modulus
* AT(OBJ) = true if on either side of two-placed object