A riot policeman uses a baton to hit a rioting University of Nairobi student in Kenya's capital Nairobi, in this May 20, 2014 file photo. (Photo by Noor Khamis/Reuters)

Soldiers, including two recruits who have brought some chickens, at Victoria prepare to board the train for the battle front. (Photo by Hulton Archive/Getty Images)

A recruitment drive during the First World War at Trafalgar Square, London. (Photo by Central Press/Getty Images)

Wrecked tanks are seen close to the road that leads to the village of Imber on December 31, 2011 on Salisbury Plain, England. (Photo by Matt Cardy/Getty Images)

Baraa Melhem plays on her sisters bike at her mothers house on February 2, 2012 in Qalandia, near Ramallah, West Bank. Baraa Melhem was held in captivity in a bathroom by her father for over nine years, and was finally rescued by Palestinian security forces after a family member notified police. (Photo by Ilia Yefimovich/Getty Images)

Ten-year-old panda Xin Yue channels Kate Winslet in Titantic at Taihu Lake National Wetland Park in the Jiangsu Province of China.

“Tasty Nature” by Dipesh Bhatt. “The blue banded bee (Amegilla cingulata) is pointing this sheath towards the flowers in preparation for sipping nectar”. Taken in Gujarat, India. (Photo by Dipesh Bhatt/2016 Royal Society of Biology Photographer of the Year competition)

A coach wipes away tears and comforts a girl who was feeling tired during gymnastics lessons at the Shanghai Yangpu Youth Amateur Athletic School in Shanghai, China, May 4, 2016. (Photo by Aly Song/Reuters)