Members of the Bavarian police and the Bundeswehr, the German armed forces, guard a vehicle checkpoint as they demonstrate a dynamic operation as part of the GETEX anti-terror exercises during a media event on March 9, 2017 in Murnau, Germany. (Photo by Philipp Guelland/Getty Images)

Daniel Cheong, a dog behaviorist and trainer, steps over a leash as he walks a pack of dogs in Arlington, Va. on November 13, 2018. (Photo by Ricky Carioti/The Washington Post)

A museum employee views “Details of Renaissance Paintings (Sandro Botticelli, Birth of Venus, 1482)” by Andy Warhol at the Victoria and Albert museum in London, Britain, March 2, 2016. The piece forms part of “Botticelli Reimagined”, an exhibition exploring the ways artists have responded to the artistic legacy of the fifteenth century artist Sandro Botticelli, and including over fifty artworks by Botticelli himself. (Photo by Toby Melville/Reuters)

Paul, 9, dumps a bucket of water over his head at a fountain near government buildings during hot weather on July 1, 2015 in Berlin, Germany. Temperatures across northern Europe are rising and in Germany a high of 36 degrees is forecast for the weekend. (Photo by Sean Gallup/Getty Images)

A Soyuz MS-11 rocket carrying Russian, American and Canadian astronauts takes off from the Baikonur Cosmodrome on December 3, 2018 before reached orbit later, the first manned mission since a failed launch in October. (Photo by Kirill Kudryavtsev/AFP Photo)

Afghan boys attend their Quran study sessions at the Islami Noor religious school on May 12, 2011 in Kandahar, Afghanistan. Despite recent multiple attacks near the city's downtown, children continue their studies at the school. (Photo by Majid Saeedi/Getty Images)

Supporters of Ratko Mladic wave flags with his picture and reading in Serbian “Serbian hero” during a rally organized by the ultra nationalist Serbian Radical Party in front of the Parliament building on May 29, 2011 in Belgrade, Serbia. Some 7,000 supporters of the former Bosnian Serb army chief Ratko Mladic, who was arrested on Thursday in a village in Serbia after 16 years on the run, took to the streets of Belgrade, to hear speeches and protest Mladic's arrest. Mladic, who is facing extradition to the The Hague, is accused of war crimes, including the 1995 massacre of 7,500 Muslin men and boys in Srebrenica. (Photo by Srdjan Stevanovic/Getty Images)

Cosplay enthusiasts Alex Lawson, 20, attends the North East Manga and Anime Convention (NemaCon) dressed as Hunni Sempai at Middlesborough Town Hall on June 18, 2011 in Middlesbrough, England. Hundreds of Manga, Anime and Cosplay enthusiasts gathered for NemaCon 2011. Cosplay is short for Costume Play where players dress and perform roles from Japanese culture, Anime and Manga art characters. Many subcultures have also evolved inspired by video games, American cartoons and comics. (Photo by Christopher Furlong/Getty Images)