sig
type 'a k
val create_key : string -> 'a Structure.Key.k
val eq_type :
'a Structure.Key.k -> 'b Structure.Key.k -> ('a, 'b) Structure.eq option
val print : 'a Structure.Key.k Pretty_utils.formatter
val compare : 'a Structure.Key.k -> 'b Structure.Key.k -> int
val equal : 'a Structure.Key.k -> 'b Structure.Key.k -> bool
val hash : 'a Structure.Key.k -> int
val tag : 'a Structure.Key.k -> int
end