A Kurdish fighter from the People's Protection Units (YPG) fires his rifle at Islamic State militants as he runs across a street in Raqqa, Syria, July 2017. (Photo by Goran Tomasevic/Reuters)

Police officers display their AI-powered smart glasses in Luoyang, Henan province, China on April 4, 2018. (Photo by Reuters/China Stringer Network)

Blossoms and dust are blown by the wind as Jasmin Ricks, left, and her sister, Jessica Ricks, center, take in the cherry blossoms near the Tidal Basin in Washington on April 12, 2018. (Photo by Matt McClain/The Washington Post)

A man transports passengers on an improvised motorized rickshaw during heavy rains in Agartala, India, April 20, 2018. (Photo by Jayanta Dey/Reuters)

Yoga students take a class with Nigerian Dwarf goats held by the 'Hello Critter Goat Yoga' team at the Golden Road Pub in Los Angeles, California on May 7, 2018. The goat yoga fitness craze is sweeping the United States with classes now held in pubs, farms and halls across the country. (Photo by Mark Ralston/AFP Photo)

Prostitutes working on 10th Ave in New York, USA on June 29, 1997. (Photo by Jon Naso/NY Daily News Archive via Getty Images)

A group of teachers and their student use makeshift raft as they cross the street during flood that hit Ranomeeto Barat village in Konawe Selatan, Sulawesi island, Indonesia, July 10, 2018. (Photo by Jojon/Reuters/Antara Foto)

Tightrope walker Tatian-Mosio Bongonga hangs from a tightrope as she pauses while scaling the Monmartre hill towards the Sacre Coeur Basilica (not pictured) in Paris, France, July 20, 2018. (Photo by Philippe Wojazer/Reuters)