-int OSHash_Add(OSHash *hash, char *key, void *data);
-int OSHash_Update(OSHash *hash, char *key, void *data);
-
+int OSHash_Add(OSHash *hash, const char *key, void *data) __attribute__((nonnull(1, 2)));
+int OSHash_Update(OSHash *hash, const char *key, void *data) __attribute__((nonnull(1, 2)));
+void *OSHash_Delete(OSHash *self, const char *key) __attribute__((nonnull));