Students from Vida Nueva School present their dinosaur robot built with recycled materials during the annual robotics fair supported by the Bolivian Education Ministry in La Paz, August 10, 2015. (Photo by David Mercado/Reuters)

Participants wearing medieval costumes re-enact the 1620 battle of Bila Hora between Bohemian Estates and Austrian Imperial with Catholic forces in Prague, Czech Republic September 18, 2016. (Photo by David W. Cerny/Reuters)

A woman looks at a swimmer getting herself warm after the annual Christmas winter swimming competition in the Vltava river in Prague December 26, 2014. (Photo by David W. Cerny/Reuters)

People with his face covered in oil and soot and carrying bull horns representing a devil join a carnival festival on February 14, 2015 in Luzon, Spain. (Photo by David Ramos/Getty Images)

Riot policemen launch tears gas canisters during clashes with coca growers from Yungas in La Paz, Bolivia February 21, 2017. (Photo by David Mercado/Reuters)

The world-famous sprinter Usain Bolt, 30, took a break from the track to celebrate Carnival as revellers doused each other with paint in Trinidad and Tobago on February 26, 2017. (Photo by David Wears/Splash News and Pictures)

A model, painted by the artist Avi Ram from Airbrush Hero, poses for a photo as part of a calendar project, at the Tower of David in Jerusalem's Old City, April 27, 2017. (Photo by Ronen Zvulun/Reuters)

A boat sails behind a woman looking through binoculars as she sits on a cliff on a sunny day in Sydney, Australia, May 29, 2016. (Photo by David Gray/Reuters)