+typedef const struct memcached_server_st *memcached_server_instance_st;
+typedef struct memcached_server_st *memcached_server_list_st;
+
+typedef struct memcached_callback_st memcached_callback_st;
+
+// The following two structures are internal, and never exposed to users.
+typedef struct memcached_string_st memcached_string_st;