AFRICA has got her first Olympic 2020 medal and it is gold. Tunisia's Ahmed Hafnaoui shocked the swimming world with a stunning victory in the men's 400m freestyle final. The 18-year-old, who qualified with the slowest time and swam the final in the outside lane, won by 0.16 seconds, with Australia's Jack McLoughlin taking silver and the USA's Kieran Smith bronze.  Three years ago,  Hafnaoui finished eighth in the same event at the 2018 Youth Olympic Games in Buenos Aires, Argentina.  Hafanoui was excited: “I just put my head under the water and that’s it. I just can’t believe it.…