US President Barack Obama speaks during his farewell address in Chicago, Illinois on January 10, 2017. Barack Obama closes the book on his presidency, with a farewell speech in Chicago that will try to lift supporters shaken by Donald Trump's shock election. / AFP / Nicholas Kamm (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)

US President Barack Obama speaks during his farewell address in Chicago, Illinois on January 10, 2017.
Barack Obama closes the book on his presidency, with a farewell speech in Chicago that will try to lift supporters shaken by Donald Trump's shock election. / AFP / Nicholas Kamm        (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)