How are sub-Saharan African economies doing? It depends on where you look, says the IMF in its latest survey of the continent, which was published this week. Regional growth will slow to just 1.4% this year, the most sluggish pace for two decades. Things look grim in Nigeria, which is mired in recession. But the Ivory Coast, a short flight away, is thundering along at a growth rate of 8%. Similar contrasts are found across the continent. Better to talk of two Africas, says the IMF, moving at different speeds.