module Utf8: sig .. end
sig
end
val fold : f:('a -> int -> [> `Malformed of string | `Uchar of Stdlib.Uchar.t ] -> 'a) -> 'a -> string -> 'a
f:('a -> int -> [> `Malformed of string | `Uchar of Stdlib.Uchar.t ] -> 'a) -> 'a -> string -> 'a