A young Chinese girl kicks during a kung-fu class at Ritan Park on June 11, 2016 in Beijing, China. Ritan, meaning “sun altar”, is among the oldest parks in Beijing, built in the early 1500s during the Ming dynasty for the emperor to make sacrifices to the sun. (Photo by Kevin Frayer/Getty Images)

Balloons are inflated at the Bristol International balloon fiesta in south west England August 6, 2015. Now in its 37th year, the Bristol International Balloon Fiesta is Europe's largest annual hot air balloon event in the city that is seen by many balloonists as the home of modern ballooning. (Photo by Toby Melville/Reuters)

A couple sunbath on the beach in Ostrowo, northern Poland, July 20, 2015. Picture taken July 20, 2015. (Photo by Kacper Pempel/Reuters)

People dressed in costumes have a break while marching during the Vijanera Festival, in the small village of Silio, northern Spain, Sunday, January 3, 2016. The Vijanera masquerade, of pre-Roman origin, is the first carnival of the year in Europe symbolizing the triumph of good over evil and involving the participation of crowds of residents wearing different masks, animal skins and brightly coloured clothing with its own complex function and symbolism and becoming the living example of the survival of archaic cults to nature. (Photo by Francisco Seco/AP Photo)

A massive sand storm cloud is close to enveloping a military camp as it rolls over Al Asad, Iraq, April 27, 2005. (Photo by Cpl. Alicia M. Garcia, U.S. Marine Corps/Reuters/U.S. Department of Defense)

Children react as they celebrate Guy Fawkes day in Soweto, South Africa, on November 5, 2014. (Photo by Siphiwe Sibeko/Reuters)

This bat gives a cheeky smile as he gobbles down his food at Singapore Zoo, on September 10, 2013. (Photo by Benny Iskander/HotSpot Media)

A dog walker on Longsands beach before sunrise in Tynemouth, UK on April 1, 2016. (Photo by Owen Humphreys/PA Wire)