type +'a fiber = 'a Lwt.t
val pp_error : error Fmt.t
val map : t -> uid -> pos:int64 -> int -> Bigstringaf.t fiber
val append : t -> uid -> Bigstringaf.t -> (unit, error) Stdlib.result fiber
val appendv :
t ->
uid ->
Bigstringaf.t list ->
(unit, error) Stdlib.result fiber