A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

Fire fighters, emergency service vehicles and a helicopter in Moskovsky Prospekt at the entrance to Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow timeon April 3, 2017. (Photo by Peter Kovalev/TASS)

A general view shows the wreckage of armed trucks on the streets of Budapest at the time of the uprising against the Soviet-supported Hungarian communist regime in 1956. The picture was taken in the period between October 23 and November 4, 1956. (Photo by Laszlo Almasi/Reuters)

British prime minister Winston Churchill (1874–1965) stops to pet a cat at Liverpool Street Station, 24th May 1952. (Photo by Keystone/Hulton Archive/Getty Images)

A chimp motions for Santa to deliver his gift during Lion Country Safari's annual Christmas with the Chimps on Thursday, December 20, 2012. (Photo by Bruce R. Bennett/The Palm Beach Post)

Jessica Shears attends the UK Premiere of “Daddy's Home 2” at Vue West End on November 16, 2017 in London, England. (Photo by Karwai Tang/WireImage)

A Yemeni soldier, pictured through a vehicle's windscreen, which was damaged by a bullet, gestures out of the window, in Marib, Yemen October 15, 2015. Marib is a city that is heavily armed even by the standards of Yemen, where the ready availability of weapons helped start civil war and is now preventing anyone coming out on top. Yemenis often say there are three guns for every person, a boast that has become an urgent concern in a country where the United Nations says the humanitarian situation is "critical". (Photo by Angus McDowall/Reuters)

A white whale wears a wreath at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, Japan, on October 3, 2012. (Photo by Associated Press)