val print :
  ?diff_command:string ->
  ?extra_patdiff_args:string list (** default: [] *) ->
  ?use_color:bool (** default: false *) ->
  file1:string ->
  file2:string ->
  unit ->
  unit
(** Diff two files. Use [diff_command] to specify what command to use. If not
    specified [patdiff] is used, with a fallback to [diff -u] if [patdiff]
    produces no differences. *)