Impala pictured in the Kruger National Park on December 7, 2007 in Mpumalanga, South Africa. (Photo by Warren Little/Getty Images)

LONDON - JUNE 04: A piece entitled “Entrance into wood” by Elke Krystufek goes on show at The Royal Academy Summer Exhibition on June 4, 2008 in London. In it's 240th year, the exhibition displays a wide range of recent work by both established and emerging artists. 10,000 artists submitted work for selection this year. (Photo by Peter Macdiarmid/Getty Images)

Former NBA player Yao Ming (R), a member of the 12th Chinese People's Political Consultative Conference (CPPCC) National Committee, is seen during an interview in Beijing, China, in this picture taken March 9, 2016. (Photo by Reuters/China Daily)

Heidi Klum attends the Heidi Klum's 16th Annual Halloween Party sponsored by GSN's Hellevator And SVEDKA Vodka At LAVO New York on October 31, 2015 in New York City. (Photo by Mike Coppola/Getty Images for Heidi Klum)

Graffiti is painted on the bathroom walls at a restaurant in the Williamsburg area of Brooklyn borough in New York, United States, October 1, 2015. Some 2.4 billion people around the world don't have access to decent sanitation and more than a billion are forced to defecate in the open, risking disease and other dangers, according to the United Nations. To mark World Toilet Day on November 19, Reuters photographers captured pictures of toilets in cities, towns and villages around the globe. (Photo by Shannon Stapleton/Reuters)

A dead crocodile is seen on Huangsha Seafood Market in Guangzhou, Guandong Province, China, 22 January 2018. Tsukiji Market of China or Huangsha Seafood Market is biggest one in Southern China and one of the biggest in China, as there are literally hundreds of different varieties of fish and seafood scattered throughout the market. (Photo by Aleksandar Plavevski/EPA/EFE)

Rooftops of solar powered houses are pictured in Ota, 80 km northwest of Tokyo in this October 28, 2008 file photo. One by one, Japan is turning off the lights at the giant oil-fired power plants that propelled it to the ranks of the world's top industrialised nations. With nuclear power in the doldrums after the Fukushima disaster, it's solar energy that is becoming the alternative. Solar power is set to become profitable in Japan as early as this quarter, according to the Japan Renewable Energy Foundation (JREF), freeing it from the need for government subsidies and making it the last of the G7 economies where the technology has become economically viable. (Photo by Yuriko Nakao/Reuters)

Li Yuming, a local farmer who is interested in scientific invention, works on his unfinished miniature submarine “Xiaguang V” on the outskirts of Wuhan, capital of central China's Hubei province August 24, 2007. “Xiaguang V”, which is 3-metre long, 1.2-metre in height, has a maximum diving depth of 20 metres, and can hold two adults and one child at the same time. The submarine will be used for tour after safety test, local media said. (Photo by Reuters/Stringer)