A migrant boy sits on railway tracks at a train station in Tovarnik, Croatia, September 20, 2015. (Photo by Antonio Bronic/Reuters)

Participants run through the streets of the Back Bay during the 16th annual Santa Speedo Run in Boston, Massachusetts, December 12, 2015. (Photo by Brian Snyder/Reuters)

Revellers react after falling in the mud at Worthy Farm in Somerset during the Glastonbury Festival, Britain, June 26, 2016. (Photo by Stoyan Nenov/Reuters)

Models and Caroline Scheufele, Artistic Director and Co-President of Chopard (C) pose during a photocall ahead of the Chopard Gold Party during the 68th Cannes Film Festival in Cannes, southern France, May 18, 2015. (Photo by Yves Herman/Reuters)

Mrs. Marie Graskamp of Milwaukee shows the different positions one might assume when entering the bomb shelter in Milwaukee September 3, 1958. This circular entrance is about three feet in diameter. This is the entrance (according to the builders) that would connect to the cellar of a home assuming the shelter was in the ground for added protection. If a bombing should occur, all members of family would proceed to the cellar and then through the circular port into the shelter. (Photo by AP Photo)

Pilot Akmal Bin Abdul Kahar watches South Korea's Black Eagles aerobatics team perform a manoeuvre during an aerial display at the Singapore Airshow at Changi Exhibition Center February 18, 2016. (Photo by Edgar Su/Reuters)

Miniature books and furniture are displayed in the "library" of the Astolat Castle, a 3 metre (9 foot) tall dollhouse, currently on display in New York November 14, 2015. Appraised at $8.5 million, the Astolat Castle, weighs 363 kg (800 pounds) and has 29 rooms, according to local media. (Photo by Lucas Jackson/Reuters)