Mark Dill and Brit Thacker practice acro-yoga as approximately 70,000 people from all over the world gather for the 30th annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. August 29, 2016. (Photo by Jim Urquhart/Reuters)

A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)

A dancer warms up backstage before the final of the 46th Prix de Lausanne, in Lausanne, Switzerland, 03 February 2018. Launched in 1973, the Prix de Lausanne is an international dance competition for young dancers aged 15 to 18. Closing the six-day event, prizes are awarded to the best of 21 finalists consisting of scholarships granting free tuition in a world-renowned dance school or dance company. (Photo by Valentin Flauraud/EPA/EFE)

In this Wednesday, September 12, 2018, file photo, vendors carry banana on their heads at a fruit and vegetable market in Peshawar, Pakistan. Pakistan says it will seek a bailout loan from the International Monetary Fund to address a mounting balance of payments crisis, Finance Minister Asad Umar said Monday. (Photo by Muhammad Sajjad/AP Photo)

Eight-year-old handicapped Chinese girl Qian Hongyan crawls with two home-made props and part of a basketball at Zhuangxia Village on January 5, 2005 in Luliang County of Qujing City, Yunnan Province, China. The girl who lost both of her legs in a traffic accident in 2000 at the age of three, struggles to live her life with a basketball as an underprop, “walking” between school and home by herself. The girl's story is widely reported in the country, and experts from China Rehabilitation Research Center has come to Qian's home to help her for rehabilitative treatment early 2005. (Photo by China Photos/Getty Images)

A general view of Hong Kong's business district is seen Thursday, August 1, 2013. (Photo by Vincent Yu/AP Photo)

An artist's impression of a growing supermassive black hole located in the early Universe is seen in this NASA handout illustration released on June 15, 2011. Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-Ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies. (Photo by Reuters/NASA/Chandra X-Ray Observatory/A.Hobart)