Passengers pose for a selfie as they wait for the Night Tube train service at Oxford Circus on the London underground system in London, Britain August 20, 2016. The London Underground is starting its first-ever overnight service, a move city leaders hope will make the British capital a truly 24-hour city and bolster the local economy. (Photo by Paul Hackett/Reuters)

A man takes a selfie in front of a fire from oil that has been set ablaze in the Qayyarah area, some 60 kilometres (35 miles) south of Mosul, on October 19, 2016, during an operation by Iraqi forces against Islamic State (IS) group jihadists to retake the main hub city. In the biggest Iraqi military operation in years, forces have retaken dozens of villages, mostly south and east of Mosul, and are planning multiple assaults for October 20. (Photo by Yasin Akgul/AFP Photo)

A relative, right, breaks down as rescuers carry the body of a victim after 14 coaches of an overnight passenger train rolled off the track near Pukhrayan village Kanpur Dehat district, Uttar Pradesh state, India, Sunday, November 20, 2016. Dozens were killed and dozens more were injured in the accident. (Photo by Rajesh Kumar Singh/AP Photo)

A Pakistani devotee dances to celebrate the three-day annual festival to pay tribute to the famous saint Al-Sheikh Ali Bin Usman Al-Hajveri known as Data Ganjbaksh at outside his shrine in Lahore, Pakistan, Sunday, November 20, 2016. Thousands of people traveled from all over Pakistan to attend the celebrations. (Photo by K.M. Chaudary/AP Photo)

A Zimbabwean subsistence farmer holds a stunted maize cob in his field outside Harare, January 20, 2016. About 14 million people face hunger in Southern Africa because of a drought that has been exacerbated by an El Nino weather pattern, the United Nations World Food Programme (WFP) said on Monday. In Zimbabwe, 1.5 million people, more than 10 percent of the population, face hunger, WFP said. (Photo by Philimon Bulawayo/Reuters)

Aeronautics and Space engineer at France's Compagnie Maritime d'Expertises, or Comex, Arnaud Prost (C) meets with a jogger as he tests on the ground the “Gandolfi 2” underwater training suit for spacewalk, on January 20, 2016 in the calanques region (rocky inlets) of Marseille. The underwater training suit “Gandolfi 2”, developed with the European Space Agency (ESA), is designed for training astronauts underwater to simulate space gravity for the astronaut's extravehicular activities (EVAs). (Photo by Boris Horvat/AFP Photo)

A hot air ball balloon floats past while people stand in line to climb the Pyramid of the Sun and welcome the spring equinox in the pre-hispanic city of Teotihuacan, on the outskirts of Mexico City, Mexico, March 20, 2016. Spring equinox in Teotihuacán is an annual event which takes place around the 20th and 21st of March at the pre-Hispanic site of Teotihuacán, Mexico. This event is mirrored by other similar events in other pre-Hispanic sites such as Chichén Itzá and Malinalco, Mexico State. (Photo by Edgard Garrido/Reuters)

A member of the National Gendarmerie Intervention Group (GIGN) deactivates a bomb from a supposed terrorist during a training exercise in the event of a terrorist attack in collaboration with Recherche Assistance Intervention Dissuasion (RAID) and Research and Intervention Brigades (BRI) in presence of the French Interior minister Bernard Cazeneuve at la Gare Montparnasse, in central Paris on April 20, 2016. (Photo by Miguel Medina/Reuters)