Demonstrators perform a dance in front of riot policemen during a march called by students to request changes in the education system in Santiago, Chile September 5, 2017. (Photo by Ivan Alvarado/Reuters)

An art installation formed with milk churns, made by land art artist Gerard Benoit a la Guillaume, is seen at the Chenau de Mayen in the resort of Leysin, Switzerland August 7, 2015. More than 80 milk churns were placed between the Tour d'Ai and the Tour de Mayen summits at an altitude of 2,000 meters (6,561 feet) above sea level under the direction of the artist, to be photographed for his ongoing art project entitled “Milk churns without borders”. (Photo by Denis Balibouse/Reuters)

Disguised revellers parade on the occasion of the Cortege during the Carnival in Basel, Switzerland, February 17, 2016. (Photo by Georgios Kefalas/EPA)

Residents of the Brussels suburb of Molenbeek are searched by police before taking part in a memorial gathering to honour the victims of the recent deadly Paris attacks, in Brussels, Belgium, November 18, 2015. (Photo by Yves Herman/Reuters)

Models turned into “humanoid” robots pose on a train at Waterloo Station on October 2, 2016 in London, England for the launch of new Sky Atlantic TV drama Westworld. (Photo by Matt Alexander/PA Wire)

A man dressed as a “Trapajon”, representing entities of nature, poses for a picture after taking part in the Vijanera Festival in Silio, northern Spain, Sunday, Jan. 6, 2013. The Vijanera masquerade, of pre-Roman origin, is the first carnival of the year in Europe symbolizing the triumph of good over evil and involving the participation of crowds of residents wearing different masks, animal skins and brightly colored clothing with its own complex function and symbolism and becoming the living example of the survival of archaic cults to nature. (Photo by Daniel Ochoa de Olza/AP Photo)

A sun bear reacts to triple-digit temperatures at the Henry Doorly Zoo in Omaha, Nebraska, where the temperature reached 103 degrees Fahrenheit on July 6, 2012. (Photo by Nati Harnik/Associated Press)