Iraqi army soldiers fire mortars against the Islamic State militants, at Shahrazad village 2 miles (3 kilometers) east of Mosul, Iraq, Monday, November 14, 2016. A suicide bombing in Iraq targeted the Shiite sacred city of Karbala on Monday, killing at least six civilians, the latest attempt by the Islamic State group to distract from the government forces' offensive on the IS-held northern city of Mosul. (Photo by Hussein Malla/AP Photo)

Olaf Niess catches swans on the river Alster near the town hall in Hamburg, Germany, 17 November 2015. The Alster swans are moving to their ice-free winter quarters on the Eppendorf Muehlenteich millpond until spring. (Photo by Bodo Marks/EPA)

38 year old Prabhat Sinha, from Assam, carries a load of coal weighing 60kg's, supported by a head-strap, as he ascends the staircase of a coal mine on April 16, 2011 near the village of Khliehriat, in the district of Jaintia Hills, India. (Photo by Daniel Berehulak/Getty Images)

Shane Baker of Minnesota poses for a photo with adult film actress Rachel Starr at the Pornhub booth at the 2017 AVN Adult Entertainment Expo at the Hard Rock Hotel & Casino on January 18, 2017 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

Rebel fighters from the Jaish al- Fatah (or Army of Conquest) brigades manoeuver an alleged explosive- rigged make- shift armoured vehicle during a major assault on Syrian government forces West of Aleppo city on October 28, 2016 Syrian opposition fighters launched a major assault on government forces to break a months- long siege of rebel- held neighbourhoods of the battered city of Aleppo. Rebel groups including the powerful Ahrar al- Sham faction and former Al- Qaeda affiliate Fateh al- Sham Front fired waves of rockets into government- held western Aleppo, killing at least 15 civilians, a monitor said. (Photo by Omar Haj Kadour/AFP Photo)

A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

Onati Basque dancers go airborne as they perform Basque traditional dances while making their way to the front of Saint Mark's Catholic Church, Saturday, August 1, 2015, in Boise, Idaho. The annual Mass, conducted in English and Basque, was held at the church for the first time. (Photo by Kyle Green/Idaho Statesman via AP Photo)

Demonstrators hold masks depicting Colombian citizen Mile Virginia, who was murdered along with photojournalist Ruben Espinosa and three other women, during a protest in Mexico City, August 16, 2015. Espinosa, a prominent Mexican news photographer was among five people found dead in a middle-class neighborhood of the capital on July 31, 2015. Espinosa, who worked for the weekly magazine Proceso and the photo agency Cuartoscuro, had sought shelter in Mexico City earlier this summer saying he had been followed and threatened in the eastern state of Veracruz. (Photo by Tomas Bravo/Reuters)