* HASH_WANT_NEW node *new(key) -- create new node with given key.
* Doesn't check whether it already exists.
* HASH_WANT_LOOKUP node *lookup(key) -- find node with given key,
* HASH_WANT_NEW node *new(key) -- create new node with given key.
* Doesn't check whether it already exists.
* HASH_WANT_LOOKUP node *lookup(key) -- find node with given key,