module Poly: sig .. end
Poly is a convenient shorthand for Polymorphic_compare in the common case that one
    wants to use a polymorphic comparator directly in an expression, e.g. Poly.equal a
    b.
Poly is a convenient shorthand for Polymorphic_compare in the common case that one
    wants to use a polymorphic comparator directly in an expression, e.g. Poly.equal a
    b.
include Polymorphic_compare
Poly is a convenient shorthand for Polymorphic_compare in the common case that one
    wants to use a polymorphic comparator directly in an expression, e.g. Poly.equal a
    b.