+#define TAG (1ULL << 63)
+#define TAG_VALUE(v) ((uint64_t)(v) | TAG)
+#define IS_TAGGED(v) ((uint64_t)(v) & TAG)
+#define STRIP_TAG(v) ((uint64_t)(v) & ~TAG)
+
+#define DOES_NOT_EXIST 0
+#define ERROR_INVALID_OPTION (-1)
+#define ERROR_INVALID_ARGUMENT (-2)
+#define ERROR_UNSUPPORTED_FEATURE (-3)
+