A prototype Rollkers transportation device is displayed during a press event at the Mandalay Bay Convention Center for the 2015 International CES on January 4, 2015 in Las Vegas, Nevada. The product is not a skate; it balances for you and when you place it on the bottom of your shoe, it gives you the ability for faster transportation based on walking. The balance CES, the world's largest annual consumer technology trade show, runs from January 6-9 and is expected to feature 3,600 exhibitors showing off their latest products and services to about 150,000 attendees. (Photo by Ethan Miller/Getty Images)

People ride a Ferris wheel as fireworks illuminate the sky over Edinburgh, Scotland. (Photo by David Cheskin/Press Association)

Armed forces veteran Frank Simpson at the Portico library being camouflaged by body artist Carolyn Roper in Manchester, UK on May 16, 2016 as part of the #CountThemIn campaign launched on Monday by the Royal British Legion. (Photo by Jon Super/Royal British Legion/PA Wire)

David Sharp, an engineer with Lockheed Martin, displays the “Samurai Flyer”, an aviation design inspired by the maple seed, during the Association for Unmanned Vehicle Systems International Conference August 16, 2011 in Washington, DC. Lockheed Martin unveiled the new design and demonstrated vertical takeoff and landing, stable hover, and on-board video streaming of the aircraft during their demonstration. (Photo by Win McNamee/Getty Images)

A visitor poses for a picture during Sao Paulo Fashion Week in Sao Paulo, Brazil, March 16, 2017. (Photo by Nacho Doce/Reuters)

A woman sits behind a bicycle on a cold winter morning in New Delhi, December 31, 2019. (Photo by Anushree Fadnavis/Reuters)

Women are reflected in a puddle as they walk across Red Square in Moscow, Russia on April 26, 2018. (Photo by Yuri Kadobnov/AFP Photo)