Snow covers roofs, streets and the Charles River following a winter blizzard in Boston, Massachusetts January 28, 2015. A powerful blizzard struck Boston and surrounding New England on Tuesday, leaving some 4.5 million people grappling with as much as three feet of snow and coastal flooding. (Photo by Brian Snyder/Reuters)

A woman reacts as she uses a selfie stick to take a photo of herself at Tiananmen Square in Beijing, China, Thursday, April 30, 2015. Selfie sticks are gaining popular in China, and many people are using them at popular tourist destinations. (Photo by Andy Wong/AP Photo)

Residents ride on top of an overcrowded “Jeepney”, a locally manufactured public transport, along a highway in Mogpog town on Marinduque island in central Philippines April 8, 2015. (Photo by Erik De Castro/Reuters)

Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

Carved pumpkins designed by US pumpkin artist Ray Villafane are pictured during a pumpkin exhibition in Ludwigsburg, southern Germany, on September 8, 2017. (Photo by Sebastian Gollnow/AFP Photo/DPA)

Revelers celebrate during fireworks marking the start of the New Year on Copacabana beach on January 1, 2017 in Rio de Janeiro, Brazil. (Photo by Mario Tama/Getty Images)

British theoretical physicist Stephen Hawking, Cambridge University Professor and Fellow, circa 1985. Stephen Hawking, the brightest star in the firmament of science, whose insights shaped modern cosmology and inspired global audiences in the millions, has died aged 76. (Photo by Gemma Levine/Getty Images)

A local farmer Theophilus Mwendwa runs through a swarm of desert locusts to chase them away in the bush near Enziu, Kitui County, some 200km east of the capital Nairobi, Kenya, 24 January 2020. Large swarms of desert locusts have been invading Kenya for weeks, after having infested some 70 thousand hectares of land in Somalia which the United Nations Food and Agriculture Organisation (FAO) has termed the “worst situation in 25 years” in the Horn of Africa. FAO cautioned that it poses an “unprecedented threat” to food security and livelihoods in the region. (Photo by Dai Kurokawa/EPA/EFE)