The late MIT economist Rüdiger Dornbusch used to tell his students in the 1980s that there are four kinds of countries: rich, poor, Japan, and Argentina. No one frets anymore about Japan buying its way to world domination. But the world is worrying again about Argentina. The country has just suffered another textbook attack on its currency. On April 24, the yield on ten-year US Treasury bonds broke 3% for the first time since 2014. On the same day, investors began dumping Argentine pesos and seeking the security…