Battle-weary American troops withdraw from Yong San in Korea. (Photo by Keystone/Getty Images). 1950

Mario Huettenhofer, chief of the German company 3D Fab, presents his own face as 3d print during the international fairs FabCon 3.D and Rapid.Tech in Erfurt, Germany, Thursday, May 15, 2014. 130 exhibitors from all over the world present the entire world of 3D printing. The trade fairs are accompanied by specialist programs featuring 80 scientists, practitioners and trend analysts from ten countries, who will explain the latest findings, trends and applications for additive processes in industry and for 3D printing in the private sector to newcomers, experts and consumers alike. (Photo by Jens Meyer/AP Photo)

Russia's Maria Sharapova carries the torch during the opening ceremony of the 2014 Winter Olympics in Sochi, Russia, Friday, February 7, 2014. (Photo by Matt Dunham/Associated Press)

Shoppers wrestle over a television as they compete to purchase retail items on “Black Friday” at an Asda superstore in Wembley, north London November 28, 2014. Britain's high streets, malls and online sites were awash with discounts on Friday as more retailers than ever embraced U.S.-style “Black Friday” promotions, seeking to kickstart trading in the key Christmas period. In the United States the Friday following the Thanksgiving Day holiday is called Black Friday because spending usually surges and indicates the point at which American retailers begin to turn a profit for the year, or go “into the black”. (Photo by Luke MacGregor/Reuters)

Riot police walk in the street as a couple kiss on June 15, 2011 in Vancouver, Canada. Vancouver broke out in riots after their hockey team the Vancouver Canucks lost in Game Seven of the Stanley Cup Finals. (Photo by Rich Lam/Getty Images)

A model walks the runway during the Neo Fashion show during Berlin Fashion Week Autumn/Winter 2020 at Vienna House Adel's on January 13, 2020 in Berlin, Germany. (Photo by Robert Schlesinger/Getty Images for Neo.Fashion.2020)

Brenda, a Honduran girl who is seeking asylum in the U.S., is carried from the Rio Grande in distress, where she had been bathing across the river from a Brownsville, Texas U.S. Customs and Border Protection tent facility as immigration hearings were being held by video teleconference, in Matamoros, Mexico September 12, 2019. Most of the people living in an encampment near the Gateway International Bridge have been sent back under the “Remain in Mexico” program, officially named Migrant Protection Protocols (MPP). (Photo by Veronica G. Cardenas/Reuters)

A woman holds up an umbrella and license plates, one that reads “love”, during violent protests between riot police and demonstrators in the Causeway Bay district of Hong Kong on October 1, 2019. The city observes the National Day holiday to mark the 70th anniversary of communist China's founding Strife-torn Hong Kong on October 1 marked the 70th anniversary of communist China's founding with defiant “Day of Grief” protests and fresh clashes with police as pro-democracy activists ignored a ban and took to the streets across the city. (Photo by Nicolas Asfouri/AFP Photo)