Students play in their school yard on the first day of the new school term at a primary school in Baghdad, October 18, 2015. (Photo by Ahmed Saad/Reuters)

Revellers take part in a zombie parade to celebrate Halloween in Vina del Mar, October 31, 2015. (Photo by Rodrigo Garrido/Reuters)

An Egyptian passenger sits on the locomotive of a train as it leaves Cairo train station in Egypt, Wednesday, October 14, 2015. (Photo by Amr Nabil/AP Photo)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)

Ulia Matos takes part in a school of theatre, makeup and hair styling graduation contest in Havana, November 16, 2015. (Photo by Reuters/Stringer)

Atmosphere at the 84th Annual Hollywood Christmas Parade held at The Roosevelt Hotel on November 29, 2015 in Hollywood, California. (Photo by Zuma Wire/Rex Shutterstock)

An Aymara woman with a sheep waves to the crowd during a Christmas parade in La Paz, Bolivia December 12, 2015. (Photo by David Mercado/Reuters)

A man dressed as Santa Claus sits at a bus stop before an annual race in Belgrade, Serbia December 27, 2015. (Photo by Marko Djurica/Reuters)