A man rows a boat on the Dal Lake as a woman holds an umbrella during snowfall in Srinagar February 19, 2015. (Photo by Danish Ismail/Reuters)

In this Saturday, March 21, 2015 photo, a porter rests carrying supplies for the upcoming climbing season, near the Everest Base camp, Nepal. Nepal has cleared more than 300 mountaineers to climb Mount Everest after they had to abandon last year's efforts when an ice avalanche killed 16 guides in the mountain's deadliest disaster, an official said on March 20. The three-month climbing season for Everest, the world's tallest mountain, begins in March. (Photo by Tashi Sherpa/AP Photo)

In this photo taken Friday, September 4, 2015, tourists Sarah and John Scott from Worcester, England, take a step back as a male silverback mountain gorilla from the family of mountain gorillas named Amahoro, which means “peace” in the Rwandan language, unexpectedly steps out from the bush to cross their path in the dense forest on the slopes of Mount Bisoke volcano in Volcanoes National Park, northern Rwanda. Deep in Rwanda's steep-sloped forest, increasing numbers of tourists are heading to see the mountain gorillas, a subspecies whose total population is an estimated 900 and who also live in neighboring Uganda and Congo, fueling an industry seen as key to the welfare of the critically endangered species as well as Rwanda's economy. (Photo by Ben Curtis/AP Photo)

A man in “Red Army” garb hits the pavement during a simulated attack during a re-staging of part of the Long March in Jinggangshan September 14, 2017. The scene brings alive an extraordinary chapter in China's history that established the supremacy of Chairman Mao Zedong and the Communist Party. Deep in the mountains of Jinggangshan in the southeastern province of Jiangxi, a classroom of bank tellers participates in an ideological boot camp that plays into Chinese President Xi Jinping's drive to further consolidate his grip on power. (Photo by Thomas Peter/Reuters)

A homeless man rests on the side of a street at the old quarter of Yemen's capital Sanaa November 27, 2015. (Photo by Khaled Abdullah/Reuters)

A man rides his loaded tricycle next to three schoolgirls in Shanghai on December 11, 2015. (Photo by Johannes Eisele/AFP Photo)

In this Tuesday, December 15, 2015 photo, an Afghan man sells traditional sauces and pickles on a street in Kabul, Afghanistan. (Photo by Massoud Hossaini/AP Photo)

A man smokes marijuana during a demonstration in support of the legalization of marijuana in Medellin, May 2, 2015. (Photo by Fredy Builes/Reuters)