Parameters
Signature
val replace_if_exists : key -> value -> unit Lwt.tval remove : key -> unit Lwt.tval modify_opt : key -> (value option -> value option) -> unit Lwt.tval length : unit -> int Lwt.tval iter : 
  ?count:int64 ->
  ?gt:key ->
  ?geq:key ->
  ?lt:key ->
  ?leq:key ->
  (key -> value -> unit Lwt.t) ->
  unit Lwt.tval fold : 
  ?count:int64 ->
  ?gt:key ->
  ?geq:key ->
  ?lt:key ->
  ?leq:key ->
  (key -> value -> 'a -> 'a Lwt.t) ->
  'a ->
  'a Lwt.tval iter_block : 
  ?count:int64 ->
  ?gt:key ->
  ?geq:key ->
  ?lt:key ->
  ?leq:key ->
  (key -> value -> unit) ->
  unit Lwt.tval iter_batch : 
  ?count:int64 ->
  ?gt:key ->
  ?geq:key ->
  ?lt:key ->
  ?leq:key ->
  ((key * value) list -> unit Lwt.t) ->
  unit Lwt.t