+ | "comment()" -> COMMENT
+ | '@' ncname -> ATTNAME (L.utf8_lexeme lexbuf)
+ | "processing-instruction()" -> PI ""
+ | "processing-instruction('"ncname"')"
+ | "processing-instruction(\""ncname"\")"->
+ let s = L.utf8_lexeme lexbuf in
+ PI (String.sub s 24 (String.length s - 26))