Yang Shiguang, 77, performs stunts at a park in Xi'an, Shaanxi province, September 3, 2013. Yang has been a member of a stunt performance club since 2007, after retiring from a research institution. (Photo by Reuters/China Daily)

Christian people crowd a bush taxi on a road 55km north of Bangui as they are on their way to the capital where they expect to sell some products on the market on January 19, 2014. Fresh fighting broke out in the strife-torn Central African Republic on the eve of an announcement on Sunday of the candidates seeking to become the new interim president. Sectarian violence has gripped the landlocked country after a March 2013 coup launched by the mostly Muslim Seleka rebels, and the UN has warned that the bloodshed could turn into genocide. (Photo by Eric Feferberg/AFP Photo)

A woman jumps as a friend (not seen) takes a photo in front of a large drawing of Pope Francis depicting him as a superhero near the Vatican January 29, 2014. The Argentinian Pope is shown taking off into air with his right fist clenched in a classic Superman style. (Photo by Alessandro Bianchi/Reuters)

Bison along the Bitterroot Valley's Eastside Highway north of Stevensville, Montana, are covered in snow following a blizzard on November 23, 2010. (Photo by Perry Backus/The Missoulian)

Employees of a food stand take pictures of Titan, a robot created by England Cyberstein Robots, performing at the Danilovsly market in downtown of Moscow, Russia, 12 May 2014. Titan visited to Moscow to attend “Bal Robotov”, an interactive exhibition of the most recent advances in robotics which will be opened on 15 May in Artplay Moscow exhibition center. Titan worked alongside superstars including Will.i.am, Rihanna, Will Smith and Jackie Chan. (Photo by Sergei Ilnitsky/EPA)

Activists attend a parade to demand rights of gender equality to LGBT community members in Santiago, Chile, November 25, 2017. (Photo by Ivan Alvarado/Reuters)

More than 400 people stripped off and ran into freezing waters to celebrate the autumn equinox – and raise money for charity at Druridge Bay, Britain, September 25, 2016. It was the largest turnout the North East Skinny Dip has ever seen in its five-year history, and it was also the first time it has ever rained on the morning of the event. Revellers gathered from 5.30am on Sunday at Druridge Bay, in Northumberland, before baring all in the North Sea. (Photo by David Charlton Photography)

In this October 5, 2016 photo a man looks at the work “Not to be Reproduced” by Rene Magritte at the Kunsthalle art gallery in Hamburg, Germany. The exhibition, which runs from Oct. 7, 2016 until Jan. 22, 2017, features more than 150 masterpieces of surrealism from four of the most significant European private collections of the 20th century. (Photo by Daniel Reinhardt/DPA via AP Photo)