FOR AN example of how not to do it, I look with confidence to Mexico. President Zedil- lo's government, in office for a month, ran into heavy weather and has cast the peso overboard, to float or (of course) to sink. We have seen it all before. I remember a week- end in Washington when the bankers, assem- bled for an International Monetary Fund meeting, made a sudden rush on the hotel bookshop. A travel guide, responding posi- tively to financial crisis, had come out with a strong cover story: 'Busted peso special where to get laid for five bucks'.