A boy carries empty sacks after bringing different types of plastic materials to a recycling station in Khartoum North April 16, 2015. People bring bottles and other plastic materials to the station for recycling, and get paid in return. (Photo by Mohamed Nureldin Abdallah/Reuters)

Some women doing yoga pose on the hammocks during the Anti-Gravity yoga class at Svarga e-Motion Sanctuary at Dharmawangsa Square, Jakarta, Saturday, April 18, 2015. Anti-Gravity Yoga or “aerial yoga”, is a new type of yoga, originating in New York but now being practised in several countries, which combines the traditional yoga poses, pilates and dance with the use of a hammock. (Photo by Jurnasyanto Sukarno/JG Photo)

Curator Anna Reynolds with a doll called Pamela and a toy horse on wheels at the launch of the summer exhibition Royal Childhood at Buckingham Palace, London, which celebrates royal childhood with toys and family gifts belonging to the royal children when they were growing up, on April 2, 2014. (Photo by Sean Dempsey/PA Wire)

A person tries to extinguish flames as sparks fly during a wild forest fire in Valparaiso, Chile, Sunday April 13, 2014. Authorities say the fires have destroyed hundreds of homes, forced the evacuation of thousands and claimed the lives of at least seven people. (Photo by Luis Hidalgo/AP Photo)

An Israeli boy looks through the sight of a weapon during a display of Israeli Defense Forces (IDF) equipment and abilities at the West Bank settlement of Kiryat Arba, April 23, 2015, during celebrations for Israel's Independence Day, marking the 67th anniversary of the creation of the state. (Photo by Ronen Zvulun/Reuters)

French climber Alain Robert, also known as “Spiderman”, holds the flag of Nepal as he scales the Tour Montparnasse, a 210-metre (689 ft) building in central Paris, France April 28, 2015, to show support for the victims after the earthquake in Nepal. (Photo by Gonzalo Fuentes/Reuters)

Russian servicemen drive a partially covered T-14 Armata tank along a street before a rehearsal for the Victory Day parade in Moscow, Russia, April 29, 2015. Russia will celebrate the 70th anniversary of the victory over Nazi Germany in World War Two on May 9. (Photo by Maxim Zmeyev/Reuters)

Vietnamese military personnel in traditional dress take part in a parade celebrating the 40th anniversary of the end of the Vietnam War which is also remembered as the fall of Saigon, in Ho Chi Minh City, Vietnam, Thursday, April 30, 2015. (Photo by Dita Alangkara/AP Photo)