Natasha Hastings of U.S. on the starting block before the women's 400 metres heats during the 15th IAAF World Championships at the National Stadium in Beijing, China August 24, 2015. (Photo by Lucy Nicholson/Reuters)

Elementary school children play outside their classrooms as mount Sinabung volcano spews thick volcanic ash in the background on February 10, 2017 in Karo, Indonesia. Mount Sinabung is one of the most active volcanoes in Indonesia and last erupted in May 2016, killing seven people. (Photo by Albert Damanik/Barcroft Images)

Football Soccer, England vs Wales, EURO 2016, Group B, Stade Bollaert-Delelis, Lens, France on June 16, 2016. Soccer fan Laura Woods from England fixes her makeup near riot police near the Lens stadium before the England vs Wales game. (Photo by Wolfgang Rattay/Reuters)

Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

A little girl takes a picture of a lion in the zoo in Frankfurt, Germany, Tuesday, September 13, 2016. (Photo by Michael Probst/AP Photo)

Waura Indians wrestle during this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, Brazil August 25, 2013. (Photo by Ueslei Marcelino/Reuters)

Elephant polo players in action during the King's Cup Elephant Polo event 2016 final between teams King Power (blue) and The Elephant Story, in Bangkok, Thailand, March 13, 2016. Team King Power won the annual charity event, which is now in its 14th edition. This year's edition involved 18 elephants brought from tourist trekking camps in Pattaya as well as some unemployed in Surin, and a total of 10 teams encompassing over 40 players, in this event directed at raising funds to improve the lives of elephants and elephant conservation. (Photo by Diego Azubel/EPA)

A girl presents the new Oktoberfest beer festival mug in a Oktoberfest tent in Munich, southern Germany, on August 21, 2014. The world famous beer festival Oktoberfest will takes place from September 20 to October 5, 2014. (Photo by Christof Stache/AFP Photo)