module Piecewise_linear: Piecewise_linearmodule type Key =sig..end
module type S =sig..end
module Make:
module Time:Swith type key = Time.t
module Ofday:Swith type key = Ofday.t
module Span:Swith type key = Span.t
module Float:Swith type key = float
module Int:Swith type key = int