A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

Riot police use a water cannon to disperse LGBT rights activist before a Gay Pride Parade in central Istanbul, Turkey, June 28, 2015. Turkish police fired water cannon and rubber pellets to disperse a crowd gathered in central Istanbul for the city's annual gay pride parade, a Reuters cameraman at the scene said. The police appeared intent on stopping the crowd gathering near Taksim Square, the cameraman said. Taksim is a traditional rallying ground for demonstrators and saw weeks of unrest in 2013. (Photo by Kemal Aslan/Reuters)

Onati Basque dancers go airborne as they perform Basque traditional dances while making their way to the front of Saint Mark's Catholic Church, Saturday, August 1, 2015, in Boise, Idaho. The annual Mass, conducted in English and Basque, was held at the church for the first time. (Photo by Kyle Green/Idaho Statesman via AP Photo)

Drummers perform during rehearsals at the Bird's Nest National Stadium ahead of the IAAF Athletics World Championships in Beijing on August 20, 2015. The Athletics World Championships will be held at the stadium from August 22 to 30. (Photo by Greg Baker/AFP Photo)

A reveller dressed as Spider-Man takes part in a presentation at the top of a building during an annual block party known as “Enquanto isso na Sala da Justiça” (Meanwhile, in the justice room), one of the many carnival parties taking place in the neighbourhood of Olinda, Brazil February 7, 2016. (Photo by Ueslei Marcelino/Reuters)

A picture made available on 21 July 2016 shows a visitor having a meal from a toilet bowl at “Jamban Cafe” (lit. Toilet Cafe) in Semarang, Central Java, Indonesia, 16 July 2016. The cafe was created by a sanitation expert for education purposes to stress the importance of using a dedicated toilet and keeping it clean to prevent disease. (Photo by EPA/Purwanto)

A BASE jumper is pictured against the skyline shrouded in a thick haze during the Kuala Lumpur Tower International Jump in Kuala Lumpur, Malaysia, 02 October 2015. More than 100 BASE jumpers take part in this extreme sport event, which enters its 15th year. The haze hovering over Malaysia is caused by the ongoing plantation and forest fires in the nearby Indonesian provinces of Sumatra and Kalimantan. (Photo by Fazry Ismail/EPA)

A commuter gestures to Boris Johnson as he rides across Vauxhall Bridge in London, England on November 19, 2015. The London mayor was opening a cycle superhighway. (Photo by John Stillwell/PA Wire)