bug67.scala:15: constructor cannot be instantiated to expected type;
 found   : D.this.ITree[A?,B?]
 required: D.this.InsertTree[A,B]
	val ITree(t1) = insert_1(key, value, tree, s);
            ^
bug67.scala:19: no type parameters for method INode of type [A,B](D.this.Tree[A,B],scala.Int,scala.Int)D.this.INode[A,B] exist so that it can be applied to arguments (D.this.Tree[A,B],scala.Int,scala.Int)
 --- because ---
result type D.this.INode[A,B] is incompatible with expected type D.this.InsertTree[A,B]
	INode(t0,1,s);
             ^
two errors found