The cast module defines two classes, Cast and CastDict, derived from DbObject and DbObjectDict, respectively.
Cast is derived from ~pyrseas.dbobject.DbObject and represents a Postgres cast.
A cast is identified externally as cast (<source_type> AS <target_type>).
CastDict is derived from ~pyrseas.dbobject.DbObjectDict. It is a dictionary that represents the collection of casts in a database.