module type Element =sig
..end
include Datatype.S_with_collections
val id : t -> int
id k >= 0
and
equal k1 k2 ==> id k1 = id k2
Identity of a key. Must verify id k >= 0
and
equal k1 k2 ==> id k1 = id k2
val self : State.t
val pretty_debug : t Pretty_utils.formatter