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 man reacts after catching a trout with his hands during an event promoting the Ice Festival on a frozen river in Hwacheon, about 20 km (12 miles) south of the demilitarized zone separating the two Koreas, January 10, 2015. The annual ice festival, which is one of the most famous and biggest festivals in South Korea, expects to see more than 1,000,000 people attend. The festival lasts for three weeks from January 10 this year. (Photo by Kim Hong-Ji/Reuters)

Attendees look at Volkswagen's BUDD-e, a long distance electric vehicle, displayed during a press event at CES 2016 at The Chelsea at The Cosmopolitan of Las Vegas on January 5, 2016 in Las Vegas, Nevada. 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 more than 150,000 attendees. (Photo by David Becker/Getty Images)

Kagome Co's employee Shigenori Suzuki tries to eat a tomato which is fed to him by the newly-developed “Wearable Tomato” device for runners, during its unveiling event ahead of the weekend's Tokyo Marathon in Tokyo February 19, 2015. The eight-kilo (17.6-pound) contraption fits on a runner like a rucksack. It can distribute a total of seven medium-sized tomatoes, one by one, at the click of a button and supplies the runner with much needed nutrients during a long jog or race. (Photo by Toru Hanai/Reuters)

Participants wearing superhero costumes attend the World DC Comics Super Heroes event in San Martin de Valdeiglesias, near Madrid, April 18, 2015. To celebrate the anniversary of the publication of the very first Superman story, DC Comics are asking fans to help set a new world record for the largest global gathering of people dressed as DC Comics Super Heroes. (Photo by Andrea Comas/Reuters)

A People's Liberation Army (PLA) commando jumps through a fire hoop part of an exercise during an open day event at the Ngong Shuen Chau Barracks, the PLA navy base in the territory, in Hong Kong, China, 01 July 2015. Thousands of visitors attended the PLA open day yesterday and today to mark the 16th anniversary of the handover from British rule. (Photo by Jerome Favre/EPA)

Figures of Francois Fillon (L), former French prime minister, member of The Republicans political party and 2017 presidential candidate of the French centre-right, and French National Front leader Marine Le Pen are paraded through the crowd during the 133rd Carnival parade, the first major event since the city was attacked during Bastille Day celebrations last year in Nice, France, February 11, 2017. (Photo by Eric Gaillard/Reuters)

Participants of an unauthorized opposition rally gather in Tverskaya street in central Moscow on June 12, 2017. Authorities detained Russian opposition politician Alexei Navalny and hundreds of his supporters on Monday, as they mounted demonstrations across the nation against government corruption. Over 200 were detained in Moscow and Saint Petersburg an hour into the protest, according to an NGO that tracks arrests, with Navalny himself picked up by police in his building as he was headed to the event. (Photo by Vasily Maximov/AFP Photo)