lexid is a micro library to increment lexically ordered numerical
ids.

Throughout the sequence of ids, this expression will always be
true, whether you are dealing with integers or strings:

    older_id < newer_id

The left most character/digit is only used to maintain lexical
order, so that the position in the sequence is maintained in the
remaining digits.

Such ids can be useful as build or version numbers, which are often
displayed by tooling which does not understand their correct
ordering.