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)

People look at French artist Clement Briend's photographic light installation “Divine Trees”, which features images of divine figures highly revered in Asian cultures projected on trees towering over bystanders, during a media preview of the Singapore Night Festival in Singapore August 21, 2014. The Singapore Night Festival begins on Friday. (Photo by Edgar Su/Reuters)

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)

A competitor walks on tightrope during a performance in Taizhou, Zhejiang Province, China, May 7, 2016. (Photo by Reuters/China Daily)

A person stands near the “Untitled” installation of miniature elevators by Maurizio Cattelan at a preview of the Postwar and Contemporary Art Evening Sale at Christie's auction house on November 4, 2011 in New York City. The 33-inch functioning elevator installation is expected to realize $400,000-$600,000 at the November 8 auction. (Photo by Mario Tama/Getty Images)

A girl gets a helping hand across the road in Swansea, Wales, England on December 31, 2017. (Photo by Athena Picture Agency)

Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)