tree_db is a key value storage for items that have keys ordered in a tree like way.
A key consist of a list of atoms and integers where integer are normally used as array index.
An external representation is for example a.b.1.c.d for the internal key [a,b,1,c,d]. This storage makes it easy to group related data into trees that may be traversed over children and siblings. There is also support for more advanced matching.