+char *mx_dump(const struct mx_node *m);
+
+
+/** @brief Callback for simple expansions
+ * @param nargs Number of arguments
+ * @param args Pointer to array of arguments
+ * @param output Where to send output
+ * @param u User data
+ * @return 0 on success, non-zero on error
+ */
+typedef int mx_simple_callback(int nargs,
+ char **args,
+ struct sink *output,
+ void *u);
+
+/** @brief Callback for magic expansions
+ * @param nargs Number of arguments
+ * @param args Pointer to array of arguments
+ * @param output Where to send output
+ * @param u User data
+ * @return 0 on success, non-zero on error
+ */
+typedef int mx_magic_callback(int nargs,
+ const struct mx_node **args,
+ struct sink *output,
+ void *u);
+
+void mx_register(const char *name,
+ int min,
+ int max,
+ mx_simple_callback *callback);
+void mx_magic_register(const char *name,
+ int min,
+ int max,
+ mx_magic_callback *callback);
+
+void mx_register_builtin(void);
+
+int mx_expand_file(const char *path,
+ struct sink *output,
+ void *u);
+int mx_expand(const struct mx_node *m,
+ struct sink *output,
+ void *u);
+int mx_expandstr(const struct mx_node *m,
+ char **sp,
+ void *u);
+
+int mx_str2bool(const char *s);
+const char *mx_bool2str(int n);