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)

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)

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)

Indonesian activists covered with sludge from the mud volcano hold a protest during five year anniversary of the Sidoarjo mud eruption on May 29, 2011 in the subdistrict of Porong in Sidoarjo, East Java, Indonesia. (Photo by Ulet Ifansasti/Getty Images)

Humanoid robot bartender “Carl” interacts with guests at the Robots Bar and Lounge in the eastern German town of Ilmenau, July 26, 2013. “Carl”, developed and built by mechatronics engineer Ben Schaefer who runs a company for humanoid robots, prepares spirits for the mixing of cocktails and is able to interact with customers in small conversations. (Photo by Fabrizio Bensch/Reuters)

A man makes traditional candy “Matang” in preparation for the upcoming Chinese Lunar New Year in Yuqing County, Zunyi, Guizhou Province, China, January 18, 2016. (Photo by Reuters/China Daily)