A fellow officer comes to the aid of injured patrolman C.V. Satt, who was pelted with rocks and beer bottles during a clash between police and relief demonstrators in Denver September 23, 1935. (Photo by Henry G. Eisenhand/AP Photo)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Turkana tribesmen walk with guns to protect their cattle from rival tribes near Baragoy, Kenya August 4, 2017. (Photo by Goran Tomasevic/Reuters)

A Russian police officer detains a teenager during rally protesting retirement age hikes in St. Petersburg, Russia, Sunday, September 9, 2018. A government plan to increase the age for collecting state pensions brought protests across Russia's 11 time zones on Sunday even though the opposition leader who called them was in jail. Nearly 300 people were reported arrested. (Photo by Roman Pimenov/Interpress photo via AP Photo)

Valeria Ruiz, 10, from Colombia, does a cartwheel while visiting the U.S. Capitol, as Republican members of the House continue to work towards electing a new Speaker of the House in Washington, U.S., October 9, 2023. (Photo by Kevin Lamarque/Reuters)

A three wheeled “cabin” scooter manufactured by German aircraft engineers Messerschmitt & Co at factories in Regensburg. (Photo by Hans Enzwieser/BIPs/Getty Images). 1955

A life-size robot named “Mark 1”, built by product and graphic designer Ricky Ma, 42, is seen in Hong Kong, China March 31, 2016. Ma, a robot enthusiast, spent a year-and-a half and more than HK$400,000 ($51,000) to create the humanoid robot, which is modelled after a Hollywood star, to fulfil his childhood dream. The eyes of the robot include face and color tracking functions. (Photo by Bobby Yip/Reuters)