People take photos with the skyline of the central business district in Singapore on September 10, 2015. (Photo by Edgar Su/Reuters)

Customers ride escalators at a shopping mall in central Moscow, Russia on March 2, 2019. (Photo by Mladen Antonov/AFP Photo)

A pink elephant balloon, one of the entries in the Canadian Hot Air Balloon Championships, lands in a field in High River September 27, 2013. The event is a qualifier for the World Hot Air Balloon Championships in Sao Paulo in 2014. (Photo by Mike Sturk/Reuters)

A woman jumps over a puddle as she crosses a street after a torrential downpour in the South Beach part of Miami, July 18, 2014. (Photo by Carlo Allegri/Reuters)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

A woman stands in a gift shop in central Rason city, part of the special economic zone northeast of Pyongyang, in this August 30, 2011 file photo. North Korea is a militarized, male-dominated society, but it is women who are making the money as the insular nation allows an unofficial market-based economy to take shape. (Photo by Carlos Barria/Reuters)

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

Devil Ark manager Dean Reid reacts as Tasmanian Devil joeys climb on him before the first shipment of healthy and genetically diverse devils to the island state of Tasmania leave the Devil Ark sanctuary in Barrington Tops on Australia's mainland, November 17, 2015. The largest group so far of disease-free Tasmanian devils has been released in the wild, as part of plans to save the carnivorous marsupials from a cancer threatening them with extinction. (Photo by Jason Reed/Reuters)