Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s

A man flies a kite made of 110 Tukkal or paper lanterns for the Hindu festival of “Makar Sankranti”, which marks the start of spring, in Ahmedabad January 13, 2011. (Photo by Amit Dave/Reuters)

A pilot looks up from a U.S. F-22 Raptor fighter as it prepares to refuel in mid-air with a KC-135 refuelling plane over European airspace during a flight to Britain from Mihail Kogalniceanu air base in Romania April 25, 2016. (Photo by Toby Melville/Reuters)

Visitors looks at the flying car Pegasus 1, built by French entrepreneur Jerome Dauffy at Paris Air Show, in Le Bourget, east of Paris, France, Tuesday, June 20, 2017. Aviation professionals and spectators are expected at this week's Paris Air Show, coming in, in a thousands from around the world to make business deals. (Photo by Michel Euler/AP Photo)

A professional bull rider participates in a bull riding exhibition at the premiere of “The Longest Ride” at the TCL Chinese Theatre on Monday, April 6, 2015, in Los Angeles. (Photo by Chris Pizzello/Invision/AP Photo)

South Korean police officers show their martial arts' skills during the official launch ceremony of the 2012 Seoul Nuclear Security Summit on February 15, 2012 in Seoul, South Korea. The Korean National Police Agency launched a security squad, exclusively established for the successful hosting of the 2012 Seoul Nuclear Security Summit. The 2012 Seoul Nuclear Security Summit will be held in Seoul from March 26-27, 2012. (Photo by Chung Sung-Jun/Getty Images)

Zoo keepers feed crocodiles in their enclosure at the Madras Crocodile Bank, closed due to the outbreak of coronavirus disease (COVID-19), in Mahabalipuram, India, August 3, 2020. (Photo by P. Ravikumar/Reuters)

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