val is_blank : char -> bool
val trim : string -> string
val split_lines : string -> string list
val starts_with : prefix:string -> string -> bool
val start_substr : prefix:string -> string -> bool * string
val cmp_float : ?epsilon:float -> float -> float -> bool
val mapi : ('a -> int -> 'b) -> 'a list -> 'b list
val fold_lefti : ('a -> 'b -> int -> 'a) -> 'a -> 'b list -> 'a
val time_fun : ('a -> 'b) -> 'a -> float * 'b
val date_iso8601 : ?tz:bool -> float -> string
val failwithf : ('a, unit, string, 'b) format4 -> 'a
val opt : ('a -> unit) -> 'a option -> unit
val fqdn : unit -> string
val shardf : int -> string
val make_counter : unit -> (unit -> ('a * int) list) * ('a -> unit)