A dancer performs before a judging panel during the World Irish Dancing Championships in Dublin, Ireland on April 11, 2017. The April 9-16 event draws some 5,000 performers from Ireland and overseas, including from both the Irish diaspora in places like the United States and Australia as well as less likely countries such as Russia and Japan. (Photo by Clodagh Kilcoyne/Reuters)

Anne Leanzo, of Virginia, plays Ash from the Evil Dead movie and her daughter Gina, 15, plays Lilith from the Borderlands video game during Comic-Con 2017 in San Diego, California, July 22, 2017. (Photo by Bill Wechter/AFP Photo)

A pupil of the Dao ethnic tribe returns home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

Tamberly Conway, bottom left, takes part in a large snowball fight in Dupont Circle on Sunday January 24, 2016 in Washington, DC. The Washington, DC area was blanketed by a large snow event. (Photo by Matt McClain/The Washington Post)

A students with her face smeared in coloured powder, celebrates Holi at a university campus in Chandigarh, India March 23, 2016. (Photo by Ajay Verma/Reuters)

People hold up face masks with William Shakespeare's portrait during celebrations to mark the 400th anniversary of the playwright's death in the city of his birth, Stratford-Upon-Avon, Britain, April 23, 2016. (Photo by Dylan Martinez/Reuters)

Developed for the British American Ambulance Corps, this new motorcycle ambulance is capable of speeding wounded soldiers 90 miles an hour from the front lines to field hospitals. Its springs are synchronized with the patient's heartbeat to avoid increasing fever when traveling over various Terrain. Viewing it in New York August 27, 1941, are left to right: constable Herbert Scott of England, driver; William E. Detlor, whose firm developed the vehicle; M. W. Stand, inspector-general of Civilian Defense, and Maj. Edward Riekert, also. (Photo by AP Photo)

Mrs. Marie Graskamp of Milwaukee shows the different positions one might assume when entering the bomb shelter in Milwaukee September 3, 1958. This circular entrance is about three feet in diameter. This is the entrance (according to the builders) that would connect to the cellar of a home assuming the shelter was in the ground for added protection. If a bombing should occur, all members of family would proceed to the cellar and then through the circular port into the shelter. (Photo by AP Photo)