LetTuple definition in the extractor

src/main/scala/leon/purescala/Extractors.scala

@@ -73,6 +73,7 @@ object Extractors {
       case ArraySelect(t1, t2) => Some((t1, t2, ArraySelect))
       case Concat(t1,t2) => Some((t1,t2,Concat))
       case ListAt(t1,t2) => Some((t1,t2,ListAt))
+      case LetTuple(binders, e, body) => Some((e, body, (e: Expr, b: Expr) => LetTuple(binders, e, body)))
       case wh@While(t1, t2) => Some((t1,t2, (t1, t2) => While(t1, t2).setInvariant(wh.invariant).setPosInfo(wh)))
       case ex: BinaryExtractable => ex.extract
       case _ => None