the optional value of this node
the descendants of this node
Gets the value for the key k.
the descendants of this node
Sets the provided value v for the key k.
the optional value of this node
An immutable implementation of a Trie (https://en.wikipedia.org/wiki/Trie).
the type param of keys in the nodes
the type param of values stored in the trie
the optional value of this node
the descendants of this node