A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

Teacher Mahajera Armani and her class of girls pose for a picture at their study open area, founded by Bangladesh Rural Advancement Committee (BRAC), outside Jalalabad city, Afghanistan September 19, 2015. (Photo by Reuters/Parwiz)

A paddler races in a giant pumpkin during the annual regatta on Lake Pisiquid in Windsor, Nova Scotia, Sunday, October 11, 2015. Participants hollow out the massive gourds and pilot them across the 500 meter course. (Photo by Andrew Vaughan/The Canadian Press via AP Photo)

A mother prays for success for her child in the college entrance examinations at a Buddhist temple in Seoul, South Korea, November 12, 2015. About 630,000 students on Thursday sat for the annual exams that could lead them to one of the country's top universities. In South Korea, there is no higher achievement than to be accepted by a prestigious university. As a result, many students prepare for these entrance exams from an early age, often studying up to 16 hours a day for years to take this test. (Photo by Kim Hong-Ji/Reuters)

A child looks at window cleaners work while dressed in sheep (C) and monkey costumes, denoting animal signs of the Chinese zodiac calendar, during an event marking the upcoming end of the year at a hotel in Tokyo, Japan, December 21, 2015. According to the zodiac calendar, 2015 is the year of the sheep and 2016 is the year of the monkey. (Photo by Thomas Peter/Reuters)

A petitioner with her grievances written on her clothes walks along a street in Beijing Tuesday, December 22, 2015. After months behind bars, Pu Zhiqiang, one of China's most prominent human rights lawyers, left a detention center Tuesday after receiving a suspended prison sentence in a case involving online comments critical of the ruling Communist Party. (Photo by Ng Han Guan/AP Photo)

A woman uses her smartphone before the Chanel Cruise Collection 2015/16 fashion show at the Dongdaemun Design Plaza in Seoul, May 4, 2015. (Photo by Thomas Peter/Reuters)

In this March 13, 2015 photo, Yohan, 4, from left, Cristian, 7, and Angelo, 6, playfully toss coca leaves into the air, singing: “I have a lot of money, look at all the money I have”, in La Mar, province of Ayacucho, Peru. Hauling cocaine out of the remote valley is about the only way to earn decent cash in this region where a farmhand earns less than $10 a day. Beyond extinguishing young lives, the practice has packed Peru's highland prisons with cocaine backpackers while their bosses evade incarceration. (Photo by Rodrigo Abd/AP Photo)