A man smashes an apple with a sword placed on the head of a man wearing a knave costume during the Easter knight event on April 21, 2014 in Berlin. The easter knight event delivers an insight into medieval lifestyle. (Photo by Rainer Jensen/AFP Photo/DPA)

Promotional models use their smartphones during their break at the Global Mobile Internet Conference in Beijing May 6, 2014. Mobile Internet industry executives, developers and investors from more than 30 countries took part in the Global Mobile Internet Conference in Beijing, the organiser said. (Photo by Kim Kyung-Hoon/Reuters)

Kirby Chambliss of the United States flies in formation with Matt Hall of Australia, Yoshihide Muroya of Japan and Nigel Lamb of Britain prior to the third stage of the Red Bull Air Race World Championship in front of the Petronas Towers in Kuala Lumpur, Malaysia, on May 15, 2014. (Photo by Joerg Mitter/Red Bull via Reuters)

This picture shows a two-year old orangutan seized from a residents house at the provincial Nature Conservation and Agency (BKSDSA) office in Banda Aceh on September 16, 2014. The critically-endangered primates population are dwindling rapidly due to poaching and rapid destruction of their forest habitat that is being converted into palm oil plantations. (Photo by Chaideer Mahyuddin/AFP Photo)

Humanoid robot bartender “Carl” interacts with guests at the Robots Bar and Lounge in the eastern German town of Ilmenau, July 26, 2013. “Carl”, developed and built by mechatronics engineer Ben Schaefer who runs a company for humanoid robots, prepares spirits for the mixing of cocktails and is able to interact with customers in small conversations. (Photo by Fabrizio Bensch/Reuters)

Soldiers take part in a drill during a heavy snow in Heihe, Heilongjiang province, February 26, 2014. (Photo by Reuters/China Daily)

A protestor opposed to U.S. Republican presidential candidate Donald Trump's stance on immigration clashes with Trump supporters at a rally in Norcross, Georgia October 10, 2015. (Photo by Tami Chappell/Reuters)

Soldiers of China's People's Liberation Army (PLA) jump as part of their winter training in temperature of negative 26 degrees Celsius at China's border with Russia in Heihe, Heilongjiang province, December 14, 2015. (Photo by Reuters/Stringer)