module Map:Association tables over ordered types.sig..end
   This module implements applicative association tables, also known as
   finite maps or dictionaries, given a total ordering function
   over the keys.
   All operations over maps are purely applicative (no side-effects).
   The implementation uses balanced binary trees, and therefore searching
   and insertion take time logarithmic in the size of the map.
module type OrderedType =sig..end
Map.Make.
module type S =sig..end
Map.Make.
module Make: