A South Sudanese People Liberation Army (SPLA) soldier patrols the streets in Malakal on January 21, 2014. (Photo by Harrison Ngethi/AFP Photo)

Swiss rescue workers wheel a wounded person on a stretcher after two regional trains crashed head on near Granges-Pres-Marnand near Payerne in western Switzerland July 29, 2013. The two trains collided in the Swiss canton of Vaud on Monday evening, injuring about 40 people, four seriously, Swiss news agency ATS reported. There was no immediate report of any deaths in the crash. (Photo by Denis Balibouse/Reuters)

A German Shepard bares its teeth during Schutzhund attack dog training at Witmer-Tyson Imports February 14, 2002 in Newark, CA. (Photo by Justin Sullivan/Getty Images)

Revellers celebrate the start of the carnival season, a season of controlled raucous fun that reaches a climax during the days before Ash Wednesday and the start of Lent, at 11.11 am in Cologne, Germany, November 11, 2016. (Photo by Wolfgang Rattay/Reuters)

The "Skylanders Eruptor" balloon moves by people on balconies during the 89th Macy's Thanksgiving Day Parade in the Manhattan borough of New York, November 26, 2015. (Photo by Andrew Kelly/Reuters)

A helicopter drops water over a wildfire as a firefighter works to contain it in Benahavis, southern Spain, May 19, 2015. (Photo by Jon Nazca/Reuters)

Women dance in costume during the West Indian Day Parade in Brooklyn, New York September 7, 2015. The parade, which takes place annually, celebrates Caribbean culture and history. (Photo by Andrew Kelly/Reuters)

Myanmar's military parade to mark the 72nd Armed Forces Day in the capital Naypyitaw, Myanmar March 27, 2017. (Photo by Soe Zeya Tun/Reuters)