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)

A large molded bust of Edward Snowden is pictured in Fort Greene Park at the Brooklyn borough of New York in this April 6, 2015 picture provided by ANIMALNewYork. A group of anonymous artists erected the 4-foot-tall bronze statue of Snowden, the former U.S. spy agency contractor famous for leaking classified information, in a New York City park overnight, officials said on Monday. (Photo by Aymann Ismail/Reuters/ANIMALNewYork)

A giant size figure of the United States' goalkeeper Tim Howard is displayed outside a shopping mall in Hong Kong, Thursday, June 12, 2014, to promote the upcoming 2014 World Cup in Brazil. A total of seven 3.5 meters to 4 meters (11 feet 6 inch to 13 feet one inch) tall figures of famous players attract many soccer fans. (Photo by Vincent Yu/AP Photo)

Three Boeing 737 fuselages lie on an embankment on the Clark Fork River after a BNSF Railway Co train derailed Thursday near Rivulet, Montana in this picture taken July 4, 2014. A train derailment in Montana this week damaged a shipment of jetliner fuselages and other large parts on its way to Boeing Co factories in Washington state from Spirit Aerosystems, Boeing said on Saturday. (Photo by Kyle Massick/Reuters)

Krystian Herba, a Polish extreme cyclist jumps up the steps of Eureka Tower on a bicycle as he breaks a Guinness World Record at Eureka Tower on February 4, 2014 in Melbourne, Australia. Herba jumped up 2,919 steps on his bicycle in 1 hour 45 minutes without supporting himself with his hands or feet to break his own Guinness World Record. (Photo by Scott Barbour/Getty Images)

Homeless people queue to get free hot food organized by social services during frost winter day in-Kiev on December 18, 2012. Nineteen people died of exposure in Ukraine in the last 24 hours amid temperatures of minus 20 degrees Celsius (minus 4 degrees Fahrenheit), bringing the toll this month to 37, the health ministry said Tuesday. (Photo by Sergei Supinsky/AFP Photo)

Natalie Duran, wearing a mask and dressed as Catwoman, climbs on street lights in SoHo as the city continues Phase 4 of re-opening following restrictions imposed to slow the spread of coronavirus on July 25, 2020 in New York City. The fourth phase allows outdoor arts and entertainment, sporting events without fans and media production. (Photo by Alexi Rosenfeld/Getty Images)

Robots made by local enthusiasts and employees of an automobile repair workshop are seen during installation works on the outskirts of the rebel-controlled city of Donetsk, Ukraine, November 26, 2020. According to creators, who plan to open a robotics engineering park, 13-metre and 6-metre-high sculptures featuring transformer robots were made of waste metal including car components and weigh about 4 and 2 tonnes respectively. (Photo by Alexander Ermochenko/Reuters)