ctst is an implementation of a Trie, a data structure mapping string-like key to any kind of value. More specifically, it implements a close variant of a radix tree with B-Tree-like storage of node pointers.

When storing this list of words :

colored
colours
comitee
community
commuter
commuters
compacity
compact
compacted
compute
continuity

ctst builds this tree :

The differences between ctst and another Trie project, pytst are discussed in this article.