An American soldier walks ahead of an MKIV (Mark IV) British-made tank, circa 1918. (Photo by Hulton Archive/Getty Images)

Performance of the actress Asia Argento dedicated to the exhibition of the tattoo artist Marco Manzo at the Vittoriano museum in Rome, Italy on December 11, 2018. (Photo by Barbara Amendola/IPA Press)

A newly born Sitatunga calf seen at ZSL Whipsnade Zoo on November 24, 2016 in Whipsnade, England. The swamp-dwelling species, also known as a marshbuck, is Africa's only true amphibious antelope. It was snuggled up in the leaves and almost perfectly camouflaged as it mother tended it. (Photo by Tony Margiocchi/Barcroft Images)

Model Daisy Lowe presents a creation at the Katie Eary catwalk show during London Fashion Week Men's 2017 in London, Britain January 7, 2017. (Photo by Neil Hall/Reuters)

Women take a photo in the late afternoon sun during the Coachella Valley Music and Arts Festival on April 17, 2017 in Indio, California. (Photo by Carlo Allegri/Reuters)

Riot police officers in position to crack down on demonstrators during a protest against Venezuelan President Nicolas Maduro, in Caracas on April 20, 2017. Venezuelan riot police fired tear gas Thursday at groups of protesters seeking to oust President Nicolas Maduro, who have vowed new mass marches after a day of deadly unrest. Police in western Caracas broke up scores of opposition protesters trying to join a larger march, though there was no immediate repeat of Wednesday's violent clashes, which left three people dead. (Photo by Juan Barreto/AFP Photo)

A bakery worker rides a bicycle as he carries fresh bread on his head in Cairo, Egypt, February 9, 2016. (Photo by Asmaa Waguih/Reuters)

Kurdish gunmen hold their rifles in front of the burning house of a Shi'ite militiaman during clashes in Tuz Khurmato, Iraq, April 24, 2016. (Photo by Goran Tomasevic/Reuters)