Hot air balloons fly over Igualada during an early flight as part of the European Balloon Festival on July 10, 2014 in Igualada, Spain. The early morning flight of over 30 balloons was shorter than expected due to windy weather. This flight is organised as a curtain raiser for the four-day European Balloon Festival. Now is the 18th year of the most important hot air Balloon event in Spain and one of the biggest in Europe. (Photo by David Ramos/Getty Images)

In advance of Fleet Week performances, U.S. Navy Blue Angels fly above San Francisco with Team Oracle aerobatics pilots Sean D. Tucker and Jessy Panzer on Thursday, October 10, 2019. (Photo by Noah Berger/AP Photo)

Children wearing uniforms hold toy guns during a military parade game on China's National Day, at Beyou World, a centre children where can experience different kinds of professions, in Beijing, October 1, 2015. (Photo by Reuters/Stringer)

Models get ready backstage during the Mercedes-Benz Fashion Week Tbilisi in Tbilisi, Georgia, November 1, 2018. (Photo by David Mdzinarishvili/Reuters)

Russia's synchronised swimming duet Aleksandr Maltsev (L) and Darina Valitova compete in the Mixed Duet Technical preliminary during the synchronised swimming competition at the 2015 FINA World Championships in Kazan on July 25, 2015. (Photo by Christophe Simon/AFP Photo)

Schoolchildren perfom during celebrations to mark 35 years of Zimbabwe's Independence at the National sports stadium in Harare, Saturday, April 18, 2015. President Robert Mugabe, 91, the central figure in Zimbabwean politics 35 years after Independence from Britain, has led the country since 1980. (Photo by Tsvangirayi Mukwazhi/AP Photo)

A Yemeni soldier, pictured through a vehicle's windscreen, which was damaged by a bullet, gestures out of the window, in Marib, Yemen October 15, 2015. Marib is a city that is heavily armed even by the standards of Yemen, where the ready availability of weapons helped start civil war and is now preventing anyone coming out on top. Yemenis often say there are three guns for every person, a boast that has become an urgent concern in a country where the United Nations says the humanitarian situation is "critical". (Photo by Angus McDowall/Reuters)

Mud Madness at the annual Jaffa Cakes charity three-mile run at Foymore Lodge near Portadown this afternoon, on April 13, 2014. A total of a thousand competitors and fun-runners took part in the two races held over the mudstrewn endurance course. (Photo by Alan Lewis/Photopress Belfast)