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  The sprint freestyle specialist made her Olympic debut at Beijing 2008 and narrowly missed out on medals at both London 2012 and Rio 2016.
  She finished just 0.02 seconds off the podium in the 50m freestyle in Rio.
  "Stepping away from the pool is quite a scary decision," said Halsall, 26.
  Halsall won three gold and seven silver medals at the Commonwealth Games, having made her international debut at Melbourne in 2006.
  She was part of the gold medal-winning 4x100m medley relay team at the 2015 World Championships, and also won gold in the 50m backstroke at the 2016 European Aquatics Championships.
  Halsall's retirement statement in full:
  Announcing my retirement from swimming is a weird concept to me as I've never seen it as a career or a job. Just as a hobby that I've loved doing and happened to be OK at.
  However I've done it for over a decade and there are so many people who have committed time, money, wisdom and knowledge into my journey that I will forever be thankful for. Stepping away from the pool is quite a scary decision for someone who's whole adult life to date has revolved around swim, weights, diet, peeing in a pot whilst someone watched, outdoor swim camps (yey) and lots of napping.
  I am very much looking forward to the next chapter of my life and the normality of eating and drinking what I want, the only time someone watches me pee is when I leave the door open by accident and the dog comes in, and experiencing the mythical bank holidays. I will miss my daily naps and choosing to do sets of backstroke while training outdoors just to get an even tan. It's time to close this chapter of my life and move on to the next.
  Swimming has taught me so much and given me opportunities that no other career could. So for me this is just a thank you note to everyone who has supported me for being part of a fantastic set of memories.
summary: Britain's three-time Olympian Fran Halsall, who won more than 30 medals at world, European and Commonwealth level, has announced her retirement after a 10-year international career.