Children are engulfed by foam during the Bubble Show event in Beijing, China, Sunday, June 26, 2016. Thousands of residents enjoy colored foam churned out by machines along a running track at the event designed for children and parents' interaction. (Photo by Ng Han Guan/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)

Tajammu Al-Ezza brigade fighters react while firing a Grad shell towards forces of Syria's President Bashar Al-Assad stationed in Salhab village, Hama countryside, May 7, 2015. (Photo by Mohamad Bayoush/Reuters)

Chinese artist Zhou Jie takes a nap on an unfinished iron wire bed, one of her sculpture works, after lunch as a friend of hers looks on at Beijing Now Art Gallery, in Beijing August 11, 2014. Zhou started her art project titled “36 Days” on August 9, in which she would live inside an exhibition hall with an unfinished iron wire bed, some iron wire sculptures in the shape of stuffed animal dolls, a certain amount of food and her mobile phone, for 36 days. The entire process is open to visitors and she may also interact with them, according to Zhou. (Photo by Jason Lee/Reuters)

A camel herder removes the rope from the mouth of a camel at the Pushkar Fair in Rajasthan, India, November 22, 2015. Thousands of animals, mainly camels, are brought to the annual fair to be traded. (Photo by Jitendra Prakash/Reuters)

South Korean workers are seen from a crane as they work on the 123rd floor during the framing completion ceremony of the 'Lotte World Tower' in Seoul, South Kora, 22 December 2015. The building's exterior was completed in a final height of 550 meters, and 123 floors. The ceremony came five years and two months after the construction of the building began and its opening will likely take place at the end of next year when the interior work is set to be completed, the South Korean Yonhap news agency reported. The building is the highest in South Korea and the fifth highest in the world, according to Yonhap. (Photo by Jeon Heon-Kyun/EPA)

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)

People pour wine at each other during the traditional “Battle of Wine” held as part of the Haro Wine Festival in the La Rioja region in Haro, Spain, 29 June 2016. Every year on 29 June inhabitants and tourists celebrate San Pedro's day by trowing at each other thousands of liters of Riojan wine. (Photo by Abel Alonso/EPA)