Fighters of the Free Syrian Army fire an anti-aircraft weapon in the rebel-held Mashhad area in southeastern Aleppo, on December 12, 2016, as they battle Syrian government forces during an operation to retake the embattled city. The crucial battle for Aleppo entered its “final phase” after Syrian rebels retreated into a small pocket of their former bastion in the face of new army advances. The retreat leaves opposition fighters confined to just a handful of neighbourhoods in southeast Aleppo, the largest of them Sukkari and Mashhad. (Photo by AFP Photo/Stringer)

A three-seater Toyota Kikai concept car is displayed during the 2016 CES trade show in Las Vegas, Nevada January 8, 2016. (Photo by Steve Marcus/Reuters)

Tourists ice skate at night on the Eiffel Tower's skating rink in Paris December 9, 2014. The skating rink, located on the first level of the Eiffel Tower, opens to the public as part of the Christmas holiday season. (Photo by Charles Platiau/Reuters)

A visitor takes a photo of a boulder plastic made of synthetic material called “To be in Limbo” hangs from the ceiling of the 20 meter high Jesuit Church in Vienna, Austria, Tuesday, November 25, 2014. The eight meter high, hollow and 700 kilogram heavy sculpture from the artists group Steinbrener/Dempf and Huber is supposed to symbolize faith and its threatening moments. The installation will remain until April 19, 2015 and then move to a church in Hamburg, Germany. (Photo by Ronald Zak/AP Photo)

A model presents a creation from the Gareth Pugh Spring/Summer 2016 collection during London Fashion Week in London, Britain September 19, 2015. (Photo by Suzanne Plunkett/Reuters)

An Aden civilian crouching in terror as British soldiers threaten him during Arabian demonstrations in Crater. (Photo by Express Newspapers/Getty Images). 1967

In this March 18, 2015 photo, a boy rides a mechanical bull for children at the Texcoco Fair on the outskirts of Mexico City. In Mexico, these types of fairs date back to Spanish colonial times, and in some smaller communities they are organized around the feast days of Roman Catholic saints. (Photo by Eduardo Verdugo/AP Photo)

In this May 2, 2015 photo, skywriter Nathan Hammond releases smoke as he writes messages of hope and love over New Orleans, during the New Orleans Jazz & Heritage Festival. Hammond was commissioned by local entrepreneur, Frank Scurlock, who said the messages were simply his way of reminding people that goodness can still flourish in a world that seems increasingly marred by violence. (Photo by Gerald Herbert/AP Photo)