// It appears that soot does not automatically
// release the hierarchy.
Hierarchy hierarchy = Scene.v().getActiveHierarchy();
if (expr instanceof SpecialInvokeExpr) {
SootMethod target = hierarchy.resolveSpecialDispatch(
(SpecialInvokeExpr) expr, invokedMethod);
Scene.v().releaseActiveHierarchy();
_mergeFlow(out, target);
} else if (expr instanceof InstanceInvokeExpr) {
Type baseType = ((InstanceInvokeExpr) expr).getBase()