An Iraqi soldier stands guard as a pipeline burns in the background after an explosion 30 kilometers (20 miles) northeast of Tikrit, Iraq, Monday, February 11, 2008. (Photo by Bassem Daham/AP Photo)

Armed Yemeni children sit in the back of a pick up truck with fighters loyal to Yemen's Saudi-backed President Abedrabbo Mansour Hadi in the Dar saad neighbourhood of the southern Yemeni city of Aden on May 10, 2015, as they continue to battle Shiite Huthi rebels. (Photo by Saleh Al-Obeidi/AFP Photo)

Women with their faces painted as various Hindu deities take part in a celebration a day after the first democratic constitution was announced in Kathmandu, Nepal September 21, 2015. Nepal adopted its first full democratic constitution on Sunday, a historic step for a nation that has witnessed war, a palace massacre and devastating earthquakes since a campaign to create a modern state began more than 65 years ago. (Photo by Navesh Chitrakar/Reuters)

A member of the Philippine National Police stands guard as he detains people as part of the “Rid the Streets Of Drinkers and Youth” operation on a main road in Las Pinas city, metro Manila, Philippines June 1, 2016. (Photo by Romeo Ranoco/Reuters)

A woman leaves with her television set, as she and others are evicted from their apartment blocks close to the site of last week's building collapse, after their homes were deemed unfit for habitation and marked for demolition, in the Huruma neighborhood of Nairobi, Kenya Friday, May 6, 2016. Following a building collapse which claimed at least 40 lives with more 80 people still unaccounted for, after severe flooding, the government has ordered the demolition of similar unsafe buildings in the area. (Photo by Ben Curtis/AP Photo)

Firefighters pull a pig as they try to rescue it from a well at a pig farm in Huanghua township of Leqing, Zhejiang province, April 25, 2014. Seven local firefighters successfully rescued a 300 kg (661 lbs) pig which fell down a well on Friday morning, local media reported. (Photo by Reuters/China Daily)

This artist image released from Japan's airline All Nippon Airways (ANA) on April 17, 2015 shows ANA's Boeing 787-9 aircraft into the colors of R2-D2 robot of Star Wars. Japanese air carrier ANA will place the special colored jetliner in service in this autumn. (Photo by AFP Photo/All Nippon Airways)

Robot couple Xiaolan (L) and Xiaotao carry trays of food at a restaurant in Jinhua, Zhejiang province, China, May 18, 2015. The restaurant, which opened on Monday, has two robots delivering food for customers. The robots were designed as a couple, Xiaolan and Xiaotao, according to local media. (Photo by Reuters/Stringer)