A rescue helicopter is shown at the Mount Everest south base camp in Nepal a day after a huge earthquake-caused avalanche killed at least 17 people, in this photo courtesy of 6summitschallenge.com taken on April 26, 2015 and released on April 27, 2015. Rescue teams, helped by clear weather, used helicopters to airlift scores of people stranded at higher altitudes, two at a time. (Photo by Reuters/6summitschallenge.com)

Members of the Cyclophonica band play instruments as they make a stop during a ride in Rio de Janeiro May 17, 2015. The Cyclophonica band was formed by a group of musicians riding bicycles around the city, mixing sport and culture and entertaining people on the streets, according to its founder Leonardo Fuks. (Photo by Pilar Olivares/Reuters)

Two men ride a motorcycle away from a fire in Athens on Friday, July 17, 2015. Greek firefighters battled large brush and forest fires on the outskirts of Athens and in the country's southern Peloponnese region Friday, where flames forced the evacuation of at least three villages and two summer camps. (Photo by Giorgos Bamboukos/InTime News via AP Photo)

A girl gets her hands decorated with traditional henna patterns at a roadside stall ahead of Eid-al Fitr to mark the end of the holy fasting month of Ramadan in Karachi, Pakistan, July 17, 2015. (Photo by Akhtar Soomro/Reuters)

An Army Sikorsky R-5 helicopter, undergoing record trials, demonstrates its lifting power by carrying 17 persons and pilot aloft as female onlookers wave in Bridgeport, Conn., January 10, 1946. During the tests records were claimed for altitude speed and both altitude and speed with payload. (Photo by Anthony Camerano/AP Photo)

Two models sit in an acrylic “ZF-Car” from the German manufacturer of the same name at the Automechanika automotive service industry trade fair in Frankfurt am Main, Germany, 12 September 2016. The Automechanika Fair runs from 13 to 17 September 2016. (Photo by Boris Rössler/EPA)

Freshmen in Zhengzhou Institute of Aeronautical Industry Management head bottles of mineral water for upright stand during military training on September 17, 2015 in Zhengzhou, Henan Province of China. More than 6,800 freshmen in the school are required to take part in the military training. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A devotee of the Chinese Ban Tha Rue shrine walks with guns pierced through his cheeks during a procession celebrating the annual vegetarian festival in Phuket, Thailand, October 17, 2015. The festival, featuring face-piercing, spirit mediums and strict vegetarianism celebrates the local Chinese community's belief that abstinence from meat and various stimulants during the ninth lunar month of the Chinese calendar will help them obtain good health and peace of mind. (Photo by Jorge Silva/Reuters)