exception Parse_error of string * string * intval parse_error : string -> string -> int -> 'aval enent : string -> int -> int -> stringval unent : Buffer.t -> string -> int -> int -> unitval subs : string -> int -> stringval ts :  [< `close | `comment | `doctype | `exclam | `lt | `question | `tag | `text  ] -> stringtype attr = string * stringand attrs = attr listand vp =    Vdata  | Vcdata  | Vopen of string * attrs * bool  | Vclose of string  | Vendand 'a v = { f : 'a v -> vp -> int -> int -> 'a v; accu : 'a; }val parse : 'a v -> string -> 'a