Vivian Odhiambo, 24, frys samosas in the trading centre of Kogelo, west of Kenya's capital Nairobi, July 14, 2015. Odhiambo said, “Obama is our hero and we wait to welcome him back home again. We in Kogelo have witnessed general growth and we are proud of being associated with the Obamas”, she added. As U.S. President Barack Obama visits Kenya, a personal connection to his father's birthplace of Kogelo dominates a trip that Kenyans view as a native son returning home. Residents from a herdsman to a housewife share their views on what Obama has achieved and what they would like to see next. (Photo by Thomas Mukoya/Reuters)

A wounded Syrian girl looks on at a make shift hospital in the rebel-held area of Douma, east of the capital Damascus, following shelling and air raids by Syrian government forces on August 22, 2015. At least 20 civilians and wounded or trapped 200 in Douma, a monitoring group said, just six days after regime air strikes killed more than 100 people and sparked international condemnation of one of the bloodiest government attacks in Syria's war. (Photo by Abd Doumany/AFP Photo)

Performers in costume perform in the rain during the parade on the second day of the Notting Hill Carnival in west London on August 31, 2015. Nearly one million people are expected by the organizers Sunday and Monday in the streets of west London's Notting Hill to celebrate Caribbean culture at a carnival considered the largest street demonstration in Europe. The Notting Hill Carnival started in the 1960s, when the area had a large population of immigrants recently arrived from the Caribbean and was notorious for its slums – a far cry from today when it is one of London's most expensive places to live. (Photo by Leon Neal/AFP Photo)

A wide-angle view shows the ascent of the shuttle Challenger on January 28, 1986. In the seconds after ignition, the rocket engines' hot blast began the process of destruction. (Photo by NASA)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. (Photo by Reuters/NASA/ESA/Hubble)

A girl walks to a synagogue of the Tzanz Hasidic dynasty community to read the Book of Esther, which tells the story of the Jewish festival of Purim, in Netanya, Israel, Wednesday, March 23, 2016. The Jewish holiday of Purim commemorates the Jews' salvation from genocide in ancient Persia, as recounted in the Book of Esther. (Photo by Ariel Schalit/AP Photo)

An Indian woman wrapped in a shawl travels with others on a bullock cart on a cold day at Jhansi district, in Bundelkhand, India, Monday, December 29, 2014. Most parts of north India Monday continued to shiver under biting cold with the mercury dipping several notches. (Photo by Rajesh Kumar Singh/AP Photo)

A Sumatran Tiger looks at visiting children from it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. The zoo's annual stocktake requires keepers to check on the numbers of every one of the 800 different animal species, including every invertebrate, bird, fish, mammal, reptile, and amphibian. (Photo by Dan Kitwood/Getty Images)