Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

People take a photograph at the Kremlin, against the backdrop of the Volga river, in the town of Nizhny Novgorod, Russia, July 10, 2015. Russia will host the 2018 FIFA World Cup soccer tournament. (Photo by Maxim Shemetov/Reuters)

Revellers pose during the 24th Street Parade dance music event in Zurich, August 29, 2015. (Photo by Arnd Wiegmann/Reuters)

A visitor poses for a photograph in front of a 3D painting depicting a Japanese Imperial army soldier at a 3D art gallery in Beijing January 16, 2015. (Photo by Kim Kyung-Hoon/Reuters)

Two men dressed as the Statue of Liberty look for tourists to pose with them for pictures in exchange for donations in New York's Times Square on January 20, 2015. (Photo by Jewel Samad/AFP Photo)

This Thursday, January 22, 2015 photo made with a long exposure shows the glow from a Noctiluca scintillans algal bloom along the seashore in Hong Kong. The luminescence, also called Sea Sparkle, is triggered by farm pollution that can be devastating to marine life and local fisheries, according to University of Georgia oceanographer Samantha Joye. Noctiluca itself does not produce neurotoxins like other similar organisms do. But its role as both prey and predator tends can eventually magnify the accumulation of toxins in the food chain, according to R. Eugene Turner at Louisiana State University. (Photo by Kin Cheung/AP Photo)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa, July 2, 2016. (Photo by Rogan Ward/Reuters)