Detainees look out from a prison cell at a compound of the Lukyanivska detention centre in Kiev, Ukraine, July 19, 2016. (Photo by Valentyn Ogirenko/Reuters)

A reveller, covered in mud, chats with friends during the Glastonbury Festival at Worthy Farm in Somerset, Britain, June 26, 2015. The outdoor festival runs from 24 to 29 June. (Photo by Dylan Martinez/Reuters)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

Lenticular cloud and zebra. (Photo by National Geographic)

French National Front party deputy Marion Marechal-Le Pen attends the questions to the government session at the National Assembly in Paris April 14, 2015. (Photo by Charles Platiau/Reuters)

Cloud inversion taken at Sunrise in Mam Tor, Derbyshire, UK on August 30, 2016. (Photo by David Zdanowicz/Rex Features/Shutterstock)

Daughter being told off by her mother. (Photo by Peter Dazeley/Getty Images)

This greedy piglet was isolated from the rest of its litter by the farmer who named it Hitler after it tried to grab all the food at feeding time. (Photo by R J Lewis/Getty Images). 1942