Labourers load a three-wheeled vehicle onto the back of a van at the Mercato market in Addis Ababa October 9, 2015. Addis Ababa's “Mercato” – Italian for “market” – is reputedly the biggest open-air market in Africa, lying in the west of the capital. (Photo by Tiksa Negeri/Reuters)

Self-employed pedicab driver Danilo Guerra, 25, uses his mobile phone as he waits for clients in downtown Havana April 12, 2016. (Photo by Alexandre Meneghini/Reuters)

Sichuan Opera performer Wu Yonghong, 26 years, of the Jinyuan Opera Company performs for villagers at the Dongyue Temple on May 2, 2016 in Cangshan, Sichuan province, China. Sichuan opera is a vibrant, centuries-old tradition that showcases the joys and challenges of daily life in rural China with tales of love, tradition, and family honor. Photo by Kevin Frayer/Getty Images)

A subway worker walks away after a train departed the station in central Pyongyang, North Korea May 7, 2016. (Photo by Damir Sagolj/Reuters)

In this photo taken on Wednesday, January 9, 2013, ahead of the Chinese lunar new year of the Snake, following the Chinese zodiac, genetically modified, auspicious, white snakes slither across the altar at the Temple of White Snakes in Taoyuan county, in north western Taiwan. Director of the temple Mr. Lo Chin-shih says the new year of the snake would be a time of steady progress, in contrast to the more turbulent nature of the outgoing year of the dragon. The Chinese new year fall on February 10. (Photo by Wally Santana/AP Photo)

Lindsay Knutson plays in the heavy snow with her family dog, Aspen, and daughter Flora Bejblik, 4, cq, as her husband Bob Bejblik, rear left, shovels, Tuesday, March 5, 2013 in southwest Minneapolis. The National Weather Service predicted a two-day snow total of 8 to 12 inches for much of southeastern and east-central Minnesota, including the Twin Cities. (Photo by Elizabeth Flores/AP Photo/The Star Tribune)

Members of an Orthodox community take part in an Easter service at a church in the village of Poteryaevka, some 200 km (124 miles) southwest of the city of Barnaul in Russia's Altai region, on April 24, 2011. (Reuters/Andrei Kasprishin)

Burger King employee Rumi Sekine shows the Kuro Diamond burger, right, and the Kuro Pearl burger at its Shibuya restaurant in Tokyo Tuesday, September 16, 2014. The international hamburger chain in Japan will launch the two new “kuro burger”, or “black burger” menus that sport buns, cheese and sauce all in black color, starting on Friday, Sept. 19, for a limited period. The buns and cheese are darkened with bamboo charcoal while the beef patties made with black-pepper are topped with the garlic sauce using squid ink. (Photo by Koji Sasahara/AP Photo)