A fighter of Libyan forces allied with the U.N.-backed government runs for cover during a battle with Islamic State fighters in Sirte, Libya, July 31, 2016. (Photo by Goran Tomasevic/Reuters)

Nepalese Hindu devotees take part in a bathing ritual on the last day of the month-long Swasthani Festival in the Hanumante River at Bhaktapur on the outskirts of Kathmandu on February 22, 2016. Devotees mark the Swasthani Festival with fasting, and with women in particular undertaking rituals in the hope of a prosperous life for her family and conjugal happiness. (Photo by Prakash Mathema/AFP Photo)

A murmuration of migrating starlings is seen across the sky in southern Israel December 31, 2015. (Photo by Amir Cohen/Reuters)

Five hundred replicas of the Stormtrooper characters from "Star Wars" are placed on the steps at the Juyongguan section of the Great Wall of China during a promotional event for "Star Wars: The Force Awakens" film, on the outskirts of Beijing, China, October 20, 2015. (Photo by Jason Lee/Reuters)

People ride bicycles in Halloween costumes during “Bike Kill 13” in the Brooklyn borough of New York City, October 29, 2016. “Bike Kill” is an annual gathering of builders and riders of home-made bicycles that culminates in a tall bike jousting competition. (Photo by Stephanie Keith/Reuters)

A young man “painting” the Eiffel Tower. (Photo by Keystone/Getty Images). 9th May 1970

An Egyptian security guard screams at people as medics bring in a stretcher to carry the wounded after the attack which killed President Anwar Sadat, October 6, 1981, as he watched a military parade. (Photo by AP Photo)

London's Regent Street was transformed into a festive wonderland as over 800,000 revellers enjoyed the Hamleys annual Christmas Toy Parade on November 19, 2017 in London, England. (Photo by Tristan Fewings/Getty Images for Hamleys)