module type Indexed2 = sig .. end
sig
end
type key1
type key2
val mem : key1 -> key2 -> bool
key1 -> key2 -> bool
val property : key1 -> key2 -> Property.t
key1 -> key2 -> Property.t
val add_hook : (key1 -> key2 -> Property.t -> unit) -> unit
(key1 -> key2 -> Property.t -> unit) -> unit