Before, if you did a lookup in a trie and then did a seq of the result,
you would get all of the children of the node that you looked up, but
you wouldn't get the value of the node itself.
This was nice when I was only getting children of the root node
because the root node never had a value and I didn't want it.
But I think it makes more since to always include the root node.
If it's not wanted, filter it out at the application level.
The hash-map trie is convenient to work with at the REPL since the
key/values are human readable and the backing data is traversible in a
fashion familiar to Clojure.
The byte-array backed trie has a slightly different API but is far more
memory efficient.
The paper that the tightly backed trie is based on can be viewed at
https://www.aclweb.org/anthology/W09-1505.pdf