+val statement: unit -> statement Grammar.Entry.e
+
+(* this callback is called before every grafite statement *)
+val set_grafite_callback:
+ (LexiconEngine.status -> ast_statement -> unit) -> unit
+
+(* this callback is called before every lexicon command *)
+val set_lexicon_callback:
+ (LexiconEngine.status -> LexiconAst.command -> unit) -> unit