Workers lay railway track in a tunnel of the Crossrail project in Stepney, east London, Britain, November 16, 2016. Crossrail, which is Europe's largest construction project, is a railway link which will connect outlying areas to the east and west of London with tunnels under the centre of the capital. (Photo by Stefan Wermuth/Reuters)

A man dressed as the “Star Wars” character Darth Vader sits on a bench in central Lviv, Ukraine, November 24, 2016. (Photo by Gleb Garanich/Reuters)

A man yells for help minutes after a Serb shell hit a crowded pedestrian walkway in Sarajevo, May 1993. Radovan Karadzic, a 70-year-old former psychiatrist, still in robust health, is the most senior political figure to be convicted by the International Criminal Tribunal for the Former Yugoslavia. He was found guilty of 10 out of 11 charges. He was acquitted of a second count of genocide in Bosnian towns. (Photo by Reuters)

Ali Asair, who has left his family behind and traveled hundreds of kilometers in search for a pasture for his animals, attends to his camel in a pastoralists' settlement in the Bandarbeyla district in Somalia's semi-autonomous region of Puntland, Somalia, 24 March 2017. According to media reports, the United Nations says only 31 percent of 864 million US dollars appeal for a drought-hit Somalia is funded. The UN said the world is facing the largest humanitarian crisis since 1945, adding that more than 20 million people are facing the threat of famine in Somalia, Yemen, South Sudan and Nigeria and 1.4 million children could die from starvation this year. (Photo by Dai Kurokawa/EPA)

Young girls carry containers filled with drinking water beside the railway station in Agartala, India, April 20, 2016. (Photo by Jayanta Dey/Reuters)

Revellers celebrate the New Year in Princes Street during Hogmanay street party celebrations in Edinburgh, Scotland January 1, 2015. (Photo by Russell Cheyne/Reuters)

A long exposure image of embers flying off burnt out trees following the wind driven wildfire ranging in the mountain area near Rancho Cucamonga late 30 April 2014. Earlier in the day more than 1,500 homes were evacuated as the Etiwanda fire charred around 1,000 acres in San Barnardino National Forest. (Photo by Stuart Palley/EPA)

This photo provided by Netflix/naturepl.com and WWF-International shows an African Elephant (Loxodonta africana) in front of double rainbow, in Masai Mara, Kenya, included in the Netflix natural history series, “Our Planet”, in collaboration with Silverback Films and WWF. The eight-part series debuts in 2019. (Photo by Andy Rouse/Naturepl/WWF-International/Netflix via AP Photo)