`sig
val add :
('a, 'b, [< `Read | `Write > `Write ]) BatHashtbl.Cap.t ->
key:'a -> data:'b -> unit
val replace :
('a, 'b, [< `Read | `Write > `Write ]) BatHashtbl.Cap.t ->
key:'a -> data:'b -> unit
val iter :
f:(key:'a -> data:'b -> unit) ->
('a, 'b, [< `Read | `Write > `Read ]) BatHashtbl.Cap.t -> unit
val fold :
f:(key:'a -> data:'b -> 'c -> 'c) ->
('a, 'b, [< `Read | `Write > `Read ]) BatHashtbl.Cap.t -> init:'c -> 'c
end`