Boys walk home for lunch from school in the village of Kogelo, west of Kenya's capital Nairobi, July 16, 2015. U.S. President Barack Obama visits Kenya and Ethiopia later this month. His ancestral home of Kogelo is home to Sarah Hussein Obama, his step-grandmother. The Kenyan village, burial place of Obama's father, features an open-pit goldmine, a pork butcher's, a school named after their most famous son and outdoor market stalls. Villagers get around by motorbike taxi or on foot while a donkey-cart transports water. Children, some of them named Obama in honour of the President, walk to and from school together. (Photo by Thomas Mukoya/Reuters)

A cat with a “stegosaurus spine” design cut into its fur is seen next to a dog at a pet shop, in Tainan, Taiwan June 19, 2016. Lee Mei-chen, Taiwanese hairdresser turned pet groomer, shaves paw prints, lion faces and characters from Japanese brand Hello Kitty on to animal backs. The teddy bear design is one of the most complex in the furry repertoire. Photo by Tyrone Siu/Reuters)

A rose lies on a plastic sheet covering a victim of a Malaysian Airlines Boeing 777 plane which was downed on Thursday near the village of Rozsypne, in the Donetsk region July 18, 2014. International prosecutors investigating the downing of flight MH17 over eastern Ukraine in 2014 say the missile that hit the plane was fired from territory controlled by Russian-backed rebels. They said the missile launcher was brought into Ukraine from Russia. All 298 people on board the Boeing 777 died when it broke apart in midair flying from Amsterdam to Kuala Lumpur. The JIT investigation's findings are meant to prepare the ground for a criminal trial. (Photo by Maxim Zmeyev/Reuters)

Children fill plastic containers with water from a well on a street, close to a neighbourhood called “The Tank” in the slum of Petare in Caracas, Venezuela, March 17, 2016. Although their nation has one of the world's biggest hydroelectric dams and vast rivers like the fabled Orinoco, Venezuelans are still suffering water and power cuts most days. The problems with stuttering services have escalated in the last few weeks: yet another headache for the OPEC nation's 30 million people already reeling from recession, the world's highest inflation rate, and scarcities of basic goods. President Nicolas Maduro blames a drought, while the opposition blames government incompetence. (Photo by Carlos Garcia Rawlins/Reuters)

A fledgling solar system containing deep within it enough water vapor to fill all the oceans on Earth five times, located in our Milky Way galaxy about 1,000 light years from Earth in the constellation Perseus. (Photo by Reuters/NASA/JPL-Caltech)

Miss Earth 2016 candidates wearing environmental statement sashes lineup during a press presentation in Manila, Philippines, 11 October 2016. Eighty three young women from around the globe converged in Manila for the international beauty event. Miss Earth is a pioneering beauty pageant that serves as a vehicle for environmental advocacy. (Photo by Mark R. Cristino/EPA)

A group of frogs hitched a lift on a passing crocodile. Clearly comfortable in the croc’s company the amphibians wait patiently for their chauffeur to move. But the bemused crocodile doesn’t appear to be going anywhere in a hurry. The hilarious images were captured by Tanto Yensen, 36, from Jakarta, Indonesia. (Photo by Tanto Yensen/Media Drum World Photo Agency)

Syrian civil defence volunteers, known as the White Helmets, rescue a boy from the rubble following a reported barrel bomb attack on the Bab al- Nairab neighbourhood of the northern Syrian city of Aleppo on November 24, 2016. (Photo by Ameer Alhalbi/AFP Photo)