A soldier eats ice cream as she visits a zoo in Pyongyang, North Korea, September 12, 2018. (Photo by Danish Siddiqui/Reuters)

Mave Grace, 11, who had part of her arm chopped off by militiamen when they attacked the village of Tchee, stands with her sister Racahele-Ngabausi, aged two, in an Internally Displaced Camp in Bunia, Ituri province, eastern Democratic Republic of Congo, April 12, 2018. (Photo by Goran Tomasevic/Reuters)

Indian Naga Sadhus, or naked holy men, participate in a procession before taking a “shahi snans”, or holy bath, at the Sangam river, the confluence of three of the holiest rivers in Hindu mythology, the Ganga, the Yamuna and the Saraswati, during Kumbh Mela festival in Allahabad, Uttar Pradesh, India, 15 January 2019. The Hindu festival is one of the biggest in India and will be held from 15 January to 04 March 2019 in Allahabad. (Photo by Rajat Gupta/EPA/EFE)

DJ David Guetta (R) and rapper Nicki Minaj perform onstage during the 2017 Billboard Music Awards at T-Mobile Arena on May 21, 2017 in Las Vegas, Nevada. (Photo by Mario Anzuoni/Reuters)

Rachel Hollon of Los Angeles was body painted as Harley Quinn at Comic-Con International in San Diego, USA on Jule 20, 2017. (Photo by K.C. Alfred/San Diego Union-Tribune via ZUMA Press/Rex Features/Shutterstock)

Chinese paramilitary guards monitoring passengers as they head to their train to travel to their hometowns for the “Spring Festival” or Lunar New Year at Nantong Railway Station in Jiangsu province, near Shanghai Travellers taking part in the world' s largest annual human migration must be home by January 27 to usher in the new year on January 28. (Photo by AFP Photo/Stringer)

German troops in Stalingrad, USSR. September 10, 1942. (Photo by TASS)

Ammunition airlift into besieged Khe Sanh, Operation Pegasus, April 1968. (Photo by Larry Burrows/AP Photo)