type duration =
  1. | OneSecond
  2. | OneMinute
  3. | TenMinutes
  4. | OneHour
  5. | OneDay
  6. | OneWeek
  7. | OneMonth
  8. | OneYear
val duration_to_yojson : duration -> Yojson.Safe.t
val pp_duration : Format.formatter -> duration -> unit
val show_duration : duration -> string
val equal_duration : duration -> duration -> bool
val duration_to_span : duration -> Ptime.span
val date_from_now : Ptime.t -> duration -> Ptime.t
val ptime_to_yojson : Ptime.t -> [> `String of string ]
val ptime_of_yojson : Yojson.Safe.t -> (Ptime.t, string) result
val ptime_of_date_string : string -> (Ptime.t, string) result
val ptime_to_date_string : Ptime.t -> string
module Span : sig ... end