This 35mm screening (which is also being shown on August 25th) is part of the Ousmane Sembene season at Close-Up Cinema. You can find all the details here.
Time Out review:
An invigorating film which tells, in leisurely fashion, of a middle-aged Dakar businessman whose social standing begins to slip when he takes a third wife and finds that he's lost his touch in bed ('xala' means impotence). There's no sniggering humour, though; instead, Sembene aims satirical thrusts at the Senegalese bourgeoisie, who impotently ape the worst aspects of their former colonial masters, particularly their corruption and extravagance (our hero, for instance, uses imported mineral water to wash his car). The jokes and details are delightful, yet there's real anger behind them, and it bursts spectacularly into view in the concluding frames.
Here (and above) is the trailer.