SilcBool silc_hash_table_replace_ext(SilcHashTable ht, void *key,
                                         void *context,
                                         SilcHashFunction hash,
                                         void *hash_user_context);

    Same as silc_hash_table_add_ext but if the `key' already exists in the
    hash table the old key and the old context will be replaced with the
    `key' and the `context. The destructor function will be called for the
    replaced key and context.

    The `hash' and `hash_user_context' are application specified hash
    function. If not provided the hash table's default is used.