Young gymnasts practice pull-up on a bar at a gymnasium of a sports school in Jiaxing, Zhejiang province April 11, 2015. (Photo by William Hong/Reuters)

Liu Xu presents a creation from The Blonds Fall 2018 collection during New York Fashion Week in New York, USA, on February 14, 2018. (Photo by Caitlin Ochs/Reuters)

Hot air balloons take to the skies as they participate in the mass assent at sunrise on the second day of the Bristol International Balloon Fiesta on August 11, 2017 in Bristol, England. More than 130 balloons have gathered for the four day event, now in its 39th year and now one of Europe's largest annual hot air balloon events, being hosted in the city that is seen by many as the home of modern ballooning. (Photo by Matt Cardy/Getty Images)

Fire fighters, emergency service vehicles and a helicopter in Moskovsky Prospekt at the entrance to Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow timeon April 3, 2017. (Photo by Peter Kovalev/TASS)

Six year old Gillian Smith preparing for the All England Stage Dancing Competition where she has previously won five certificates and a silver medal in the under sevens category. (Photo by Terry Fincher/Keystone/Getty Images). 5th July 1957

In this Monday, June 5, 2017, file photo, an Indian woman walks as se searches for recyclable materials at a garbage dumping site on the outskirts of Gauhati, Assam state, India. (Photo by Anupam Nath/AP Photo)

Spanish runner Francisco Contreras, 77, known as “Super Paco”, runs as he participates in the XVIII 101km international competition in the outskirts of Ronda, southern Spain, May 9, 2015. About 7,000 participants, including runners, mountain bikers and duathletes, run a track of 101 km (63 miles) in less than 24 hours through the “Serrania de Ronda” (Ronda Mountain Range) during this competition organised by the 4th Tercio (Regiment) “Alejandro Farnesio” of the Spanish Legion. The Puente Nuevo is 120 metres (394 feet) high over the gorge of the river that divides the city of Ronda. Picture taken using long exposure. (Photo by Jon Nazca/Reuters)

Iraqi troops fire artillery towards Islamic State (IS) group jihadists' positions in west Mosul on March 11, 2017 during the ongoing battle to retake the city from the group. (Photo by Aris Messinis/AFP Photo)