Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain March 23, 2016. The exhibition opens to the public on March 24 and runs until September 11. (Photo by Dylan Martinez/Reuters)

A picture made available on 30 March 2016 shows members of the anti-terror squad of the local paramilitary force have a training in Suining, in southwest Sichuan province, China, 29 March 2016. (Photo by Zhong Min/EPA)

South Sudanese wrestlers take part in a wrestling match for peace in Juba on April 19, 2016. The last wrestling match for peace was held in Juba the day before civil war broke out in December 2013. (Photo by Carl de Souza/AFP Photo)

Taiwanese-US artist Chin Chih Yang poses for a photograph with 30,000 aluminum cans after his performance called “Kill Me or Change” in Taipei, Taiwan, 23 April 2016. “Kill Me or Change!” is a performance piece that aims to raise awareness of the benefits of recycling and, encourage people to recycle to conserve resources. (Photo by Ritchie B. Tongo/EPA)

Tourists take a panoramic view of Kuala Lumpur from a skybox during a media preview at Kuala Lumpur Tower in Kuala Lumpur, Malaysia, 05 May 2016. Skybox, 421 metres above ground level will be the latest tourists attraction at Kuala Lumpur Tower, the 7th tallest freestanding tower in the world. (Photo by Ahmad Yusni/EPA)

A Ukrainian woman begs Ukrainian President Petro Poroshenko to stop the bombing in Donetsk after shell hit the residential area where she lives, killing two civilians in Donetsk's Kyibishevsky district, on January 29, 2015. (Photo by Manu Brabo/AFP Photo)

A policer officer hits a man with a baton as he tries to maintain order while migrants wait for trains at a temporary camp near Gevgelija, Macedonia, September 7, 2015. Several thousand migrants in Macedonia boarded trains on Sunday to travel north after spending a night in a provisional camp. Macedonia has organised trains twice a day to the north border where migrants cross into Serbia to make their way to Hungary. Since June, Macedonian authorities have said that more than 60,000 migrants have entered the country, and around 1,500 entered just in one day, mainly refugees from Syria. (Photo by Stoyan Nenov/Reuters)

Contestants of a tattoo competition pose for photographs at the China TATTOO convention in Nanning, Guangxi Zhuang Autonomous Region, China, October 24, 2015. The annual convention was held in Nanning from October 23 to 25 this year. (Photo by Reuters/Stringer)