Stones collected and categorised by shape (fish) are seen at the home workshop of Luigi Lineri in Zevio, near Verona, Italy, June 10, 2016. Luigi Lineri's home workshop is covered in stones – tens of thousands of them. They resemble animal heads, human faces and other forms, and the artist and poet believes may have been shaped by prehistoric humans. (Photo by Alessandro Bianchi/Reuters)

Participants hold smoke flares as they slide down along a chute to cross a pool of water and foam during the “Letniy Gornoluzhnik” (Summer mountain puddle rider) festival at the Bobroviy Log Fun Park near the Siberian city of Krasnoyarsk, Russia, August 21, 2016. (Photo by Ilya Naymushin/Reuters)

Members of the association historical recreation Frente del Nalon participate in the recreation of the battle: “The Siege of Oviedo” that took place during the Spanish Civil War, in Grullos, near Oviedo, in northern Spain, September 3, 2016. The Siege of Oviedo lasted from July 19 until October 16, 1936. The town garrison, under the command of Colonel Antonio Aranda Mata, declared for the uprising and held out until relieved by a Nationalist force. (Photo by Eloy Alonso/Reuters)

Visitors and car enthusiasts attend the annual Goodwood Revival historic motor racing festival, celebrating a mid-twentieth century heyday of the racing circuit, near Chichester in south England, Britain, September 9, 2016. (Photo by Toby Melville/Reuters)

World Champion Matthias Dolderer of Germany flies over the Horseshoe Bend near Lake Powell in Page, United States during the transfer flight from Indianapolis to Las Vegas to prior the final stage of the Red Bull Air Race World Championship on October 12, 2016. (Photo by Predrag Vuckovic/AFP Photo)

A displaced Iraqi boy leads his animals to safety after escaping from Islamic State controlled village of Abu Jarboa during clashes with IS militants near Mosul, Iraq November 1, 2016. (Photo by Ahmed Jadallah/Reuters)

A man in a Donald Trump mask joins hundreds of other protesters and activists as they march during a demonstration near a midtown hotel which is hosting a black-tie fund-raiser for the state Republican Party on April 14, 2016 in New York City. (Photo by Spencer Platt/Getty Images)

A riot police blocks a street during a march near a meeting attended by the Secretary-General of Organization of American State Luis Almagro and leaders from various communities in Managua, Nicaragua, December 1, 2016. (Photo by Oswaldo Rivas/Reuters)