People clash with Venezuelan National Guards as they try to cross the border to Colombia over the Francisco de Paula Santander international bridge in Urena, Venezuela December 18, 2016. (Photo by Carlos Eduardo Ramirez/Reuters)

A woman holds an elderly woman on her back to cross a flooded street after a heavy rain in Shenyang, Liaoning province on July 14, 2017. (Photo by Fred Dufour/AFP Photo)

A young boy adjusts his friend's Adolf Hitler mask during a game on a street in King's Cross, London. (Photo by William Vanderson/Getty Images). 1938

An Israeli army officer gives explanations to journalists during an army organised tour in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

Girls cry as they get separated from their family at the border line dividing Macedonia and Greece August 21, 2015. At least 1,000 migrants and refugees pressed against Macedonian police lines on the Greek-Macedonian border on Friday and at least 10 people appeared to faint in the crush. People could be heard screaming and medical workers raced to treat those who passed out or were hurt. The crush ensued after police let several hundred through into Macedonia, having kept them out since Thursday under an emergency decree. (Photo by Ognen Teofilovski/Reuters)

A participant in the Crazy Races extreme sports game competes in the cross-country obstacle race in Ufa, Russia on September 21, 2015. (Photo by TASS/Barcroft Media)

A Macedonian police officer hits a stranded migrant attempting to cross the Greek-Macedonian border, near Gevgelija, Macedonia December 2, 2015. Picture taken from the Greek side of the border. (Photo by Alexandros Avramidis/Reuters)

Runners cross the Verrazano-Narrows Bridge shortly after the start of the New York City Marathon in New York, November 2, 2014. (Photo by Lucas Jackson/Reuters)