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)

Russian artist Maria Gazanova (L) works on her "The Alive Painting" art work during the Art Krasnoyarsk annual festival in Siberian city of Krasnoyarsk, Russia November 4, 2015. (Photo by Ilya Naymushin/Reuters)

A young vendor hawks food on a market in Kara in the state of Ogun, on September 23, 2015. Nigeria imposed tight movement restrictions in the restive northeast after Boko Haram bombings that killed more than 100 raised fears of fresh attacks over the Eid al-Adha festival. The military said the use of all vehicles would be banned throughout Borno state during the Muslim festival, which is known as Sallah in Nigeria and marked with two days' public holiday from Thursday. (Photo by Pius Utomi Ekpei/AFP Photo)

A new species of monkey found in the Democratic Republic of the Congo and identified as Lesula (Cercopithecus lomamiensis) is seen in this undated photograph from an article published September 12, 2012 in the science journal PLOS One. The monkey was first seen in 2007 by researchers John and Terese Hart of the Peabody Museum of Natural History at Yale Research Project. The finding of C. lomamiensis represents only the second new species of African monkey to be discovered in the past 28 years, according to the research article. (Photo by Hart J. A., Detwiler K. M., Gilbert C. C./Reuters)

Members of the “Avalon” team wearing 14th century knight costumes fight against each other on the bank of the Yenisei River during the regional amateurs tournament of clubs of historical reconstruction, “The Battle of the Nations 2015. Siberia”, in Krasnoyarsk January 24, 2015. (Photo by Ilya Naymushin/Reuters)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)

An Israeli boy swims next to sheep belonging to a Palestinian farmer in the West Bank village of Al-Auja in the Jordan Valley on April 8, 2015 during the Jewish Passover holiday. Thousands of Israelis spent the day outdoors, picnicking and touring the country during the eight-day Passover holiday, which commemorates the Israelites' exodus from Egypt some 3,500 years ago. (Photo by Menahem Kahana/AFP Photo)

Dancers wearing new bikinis perform in front of passers-by and a line of photographers during a promotional flash mob event on a square outside Shinjuku station in Tokyo on July 18, 2016. The event was organized by the Japan Swimsuit Association to promote new swimwear. (Photo by Toru Yamanaka/AFP Photo)