Secondary school students perform a barefoot “pilgrimage of suffering” to support the Occupy Central civil disobedience movement at the Admiralty protest site in Hong Kong November 30, 2014. It has been two months since police first fired tear gas to disperse demonstrators from the main protest site in the Admiralty district next to government offices in the heart of the Asian financial centre. (Photo by Bobby Yip/Reuters)

A member of the mainly Christian “anti-balaka” (anti-machete) militia trains in the Boeing neighbourhood of Bangui, Central African Republic, on February 24, 2014. (Photo by Fred Dufour/AFP Photo)

U.S. soldiers from the 3rd Cavalry Regiment take part in an artillery exercise on forward operating base Gamberi in the Laghman province of Afghanistan December 24, 2014. (Photo by Lucas Jackson/Reuters)

The Air2 (Air Squared) floating Bluetooth speaker from Axxess CE is displayed at CES Unveiled, the opening event for the media preview days at the 2015 Consumer Electronics Show, January 4, 2015 in Las Vegas, Nevada. The speaker which levitates over its own base is one of the winners for the CES Innovation Awards and is patent pending. (Photo by Robyn Beck/AFP Photo)

An attendee tries Acton's RocketSkates at the 2015 International CES at the Sands Expo and Convention Center on January 6, 2015 in Las Vegas, Nevada. The motorized skates that you strap to your shoes are powered by Lithium Ion batteries and can go up to 12 mph. (Photo by Ethan Miller/Getty Images)

An injured woman is pictured near the Blue Parrot nightclub in Playa del Carmen, Quintana Ro state, Mexico where 5 people were killed, three of them foreigners, during a music festival on January 16, 2017. A shooting erupted at an electronic music festival in the Mexican resort of Playa del Carmen early Monday, leaving at least five people dead and sparking a stampede, the mayor said. Fifteen people were injured, some in the stampede, after at least one shooter opened fire before dawn at the Blue Parrot nightclub during the BPM festival. (Photo by Victor Vargas/AFP Photo)

France's Simon Billy gets ready to practice speed skiing on the Chabriere ski slope in Vars, on March 29, 2017. (Photo by Jean-Pierre Clatot/AFP Photo)

A woman looks at cows on the Mare e Sol beach in Coti-Chiavari, on the French Mediterranean island of Corsica, on May 17, 2017. A herd of some thirty wild cattle take up their summer residence on stretch of beach each year. (Photo by Pascal Pochard-Casabianca/AFP Photo)