Humanoid robots compete in a group match of the 20th RoboCup in Leipzig, Germany, June 30, 2016. About 3,500 participants from 45 countries and regions compete in the robot world championship until 04 July. (Photo by Sebastian Willnow/EPA)

A visitor stands in front of a portrait taken by artist Bruce Gilden at the “Masters of Photography” exhibition at the Photokina trade fair in Cologne on September 20, 2016. The fair for the photographic and imaging sector, that is running from September 20 to 25, 2016, presents products from image capture, image processing and storage to image output. Photokina also includes a program of events with congresses, workshops, symposiums and photography exhibitions. (Photo by Patrik Stollarz/AFP Photo)

2016 Rio Olympics, Swimming, Preliminary, Men's 100m Backstroke, Heats, Olympic Aquatics Stadium, Rio de Janeiro, Brazil on August 7 2016. Christopher Reid (RSA) of South Africa competes. (Photo by Dominic Ebenbichler/Reuters)

2016 Rio Olympics, Rugby, Women's Semifinals Britain vs New Zealand, Deodoro Stadium, Rio de Janeiro, Brazil on August 8, 2016. Portia Woodman (NZL) of New Zealand tackles Claire Allan (GBR) of United Kingdom. (Photo by Phil Noble/Reuters)

A Perseid meteor streaks across the sky above Inspiration Point early on August 12, 2016 in Bryce Canyon National Park, Utah. The annual display, known as the Perseid shower because the meteors appear to radiate from the constellation Perseus in the northeastern sky, is a result of Earth's orbit passing through debris from the comet Swift-Tuttle. (Photo by Ethan Miller/Getty Images)

A model train travels past a scaled model of New York's Grand Central Station built entirely with plant parts during a media preview of the 25th annual Holiday Train Show at the New York Botanical Garden in the Bronx borough of New York City, U.S., November 14, 2016. (Photo by Mike Segar/Reuters)

Maja, a 40-year-old elephant, extends her trunk into a bakery as a customer buys a newspaper while Maja took a stroll through the neighborhood with her minders from a nearby circus on July 1, 2016 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Riders negotiate a dune as they compete in the Adult Solo race at the HydroGarden Weston Beach Race in Weston- super- Mare, south west England, on October 9, 2016. Beach racing is an offshoot of enduro and motocross racing. Riders on solo motorcycles and quad bikes compete on a course marked out on a beach, with man- made jumps and sand dunes being constructed to make the course tougher. (Photo by Adrian Dennis/AFP Photo)