Knowing that every remaining episode featuring Jon Stewart is something to cherish, I suggest that some of them may be even more valuable than others. Like tonight’s, because Stewart, who is enough of a wonk to be fluent talking about the intricacies of national and global economies, has as his guest Christine Lagarde, managing director of the International Monetary Fund. Don’t look for Lagarde on, say, The Tonight Show – but don’t miss her here.