type xml = Tag of string * xml list | String of string

val tag : string -> xml list -> xml
val format : Format.formatter -> ('a, Format.formatter, unit) format -> 'a

val format_list :
  ?pp_sep:(Format.formatter -> unit -> unit) ->
  (Format.formatter -> 'a -> unit) ->
  Format.formatter ->
  'a list ->
  unit

val format_xml : Format.formatter -> xml -> unit