Tree trunks and rocks are set up to support a leaning wall of Li Yonghua's damaged cave house in an area where land is sinking next to a coal mine, in Helin village of Xiaoyi, China's Shanxi province, August 2, 2016. (Photo by Jason Lee/Reuters)

A man poses in front of a portrait of late Chinese Chairman Mao Zedong during the opening of an exhibition of Mao related art in Beijing, China, September 8, 2016. (Photo by Thomas Peter/Reuters)

Dressed up as Punxsutawney Phil, Marty Nagy, of Hallandale Beach, Fla., gives thumbs up to passers by before the start of the 12th annual Groundhog Day on Hollywood Beach, Tuesday, February 2, 2016, in Hollywood, Fla. The event, which featured breakfast and an ocean plunge, benefited the Hollywood Beach Lifeguard Competition Team. (Photo by Wilfredo Lee/AP Photo)

Arisha, 9, takes instructions from coach Younus Qambrani during an exercise session at the first women's boxing coaching camp in Karachi, Pakistan February 19, 2016. For the past six months about a dozen girls, aged 8 to 17, have gone to the Pak Shine Boxing Club after school to practice their jabs, hooks and upper cuts. (Photo by Akhtar Soomro/Reuters)

Visitors look at an artwork “Hierarchy of Prosperity” created by Indonesian artist Eko Nugroho during the VIP preview of the art fair “Art Basel” in Hong Kong, Tuesday, March 22, 2016. A set of gold-plated metal cubes, tapestries embroidered by unknown North Korean artisans and bales of cardboard waste are among the highlights of the Art Basel Hong Kong fair opening this week. (Photo by Kin Cheung/AP Photo)

Labrador puppies “Hoey” (L) and “Hatton”, named in honor of September 11, 2001 attack victims Patrick Hoey and Lenny Hatton who died in the World Trade Center, are pictured on the grounds of the Pentagon near Washington, June 28, 2011. (Photo by Jason Reed/Reuters)

An armoured vehicle surrounded by Chicago cops at the time of the American depression, 1933. (Photo by Rolls Press/Popperfoto/Getty Images)

Two holidaymakers amuse themselves with a porter's trolley whilst waiting for their train at Euston Station, London, 5th August 1939. (Photo by A. J. O'Brien/Fox Photos/Getty Images)