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)

A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

A young woman cools herself in a fountain in Budapest, Hungary July 6, 2015. Over the weekend, a heat wave has reached Hungary with temperatures topping 38 degrees Celsius (100.4 degrees Fahrenheit). (Photo by Laszlo Balogh/Reuters)

A man presents a self-made robot that local media reported is able to carry a person, in Heihe, Heilongjiang province, China, April 5, 2017. (Photo by Reuters/China Daily)

A woman smokes marijuana during the annual 4/20 marijuana rally on Parliament Hill in Ottawa, Ontario, Canada, April 20, 2017. (Photo by Chris Wattie/Reuters)

A woman looks towards part of an artwork called “Lichen! Libido! (London!) Chastity!” by Anthea Hamilton, one of the four artists shortlisted for the Turner Prize 2016, as it is displayed at the Tate Britain gallery in London, Monday, September 26, 2016. The Turner Prize aims to promote public debate around new developments in contemporary British art. (Photo by Kirsty Wigglesworth/AP Photo)

A female soldier from the honour guards prepares for a welcoming ceremony for Uruguay's President Tabare Vazquez at the Great Hall of the People in Beijing, China, October 18, 2016. (Photo by Jason Lee/Reuters)

Caoimhe Cooburn-Gray poses for a picture on St. Patrick's day in Dublin, Ireland March 17, 2016. Saint Patrick's Day is a cultural and religious celebration held on 17 March, the traditional death date of Saint Patrick (c. AD 385–461), the foremost patron saint of Ireland. Celebrations generally involve public parades and festivals, céilithe, and the wearing of shamrocks, as well as green or orange attire. (Photo by Clodagh Kilcoyne/Reuters)