The opening scene of the 2004 film Yesterday shows a mother (named Yesterday) and her daughter Beauty, walking down a deserted South African road. The daughter, maybe 5 years old, is describing her desire to transform into a bird. Why? She wants to float over to their destination, relieving her little legs of the agony of this miles-long trek.The finish line is a health clinic in a ramshackle hut. You see, Yesterday has developed this wretched, knock-you-over cough. But the line is lengthy, so they wait and wait until it’s announced that everyone else must return next Tuesday. Next Tuesday? A once-a-week doctor? Yes.