A Palestinian boy herds sheep in front of the ruins of Yasser Arafat International Airport, which was bombed by Israel in the past, in Rafah in the southern Gaza Strip February 5, 2016. Nabil Shurafa's travel agency in Gaza was once packed with clients booking flights to London, Paris, New York or cities across the Arab world. These days, he's lucky if anyone comes in, as so few people can get out. (Photo by Ibraheem Abu Mustafa/Reuters)

Female of pygmy hippopotamus called Malaya from Netherlands in zoo in Dvur Kralove nad Labem, Czech Republic, February 22, 2016. (Photo by David Tanecek/CTK via ZUMA Press)

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)

A monkey leaps into a pond on a hot day in Allahabad on May 19, 2017. According to local reports temperatures have soared in the northern Indian city to 47.28 Celsius. (Photo by Sanjay Kanojia/AFP Photo)

A family of refugees shelters under a truck carrying plastic lota, kettles used to perform Muslim ablutions in Muna Garage, Maiduguri, Nigeria February 16, 2017. (Photo by Paul Carsten/Reuters)

Nyibol Lual, 13 years old, helps her family to prepare the land for cultivation on May 31, 2017, in Panthau, Northern Bahr al Ghazal, South Sudan. The family has a small land where they cultivate sorghum. An estimated 63 per cent of the population in Northern Bahr al Ghazal is experiencing severe food insecurity, according to the latest Integrated Food Security Phase Classification (IPC) report. The situation is particularly bad in Aweil West and Aweil South counties, where the exhaustion of household food stocks and growing dependence on financially inaccessible markets have left the population facing Emergency levels of food insecurity. (Photo by Albert Gonzalez Farran/AFP Photo)

A police officer stands at a police cordon near the scene of a terror attack in London, U.K., on Sunday, June 4, 2017. A van swerved into Saturday-night crowds on London Bridge, before three men got out and went on a stabbing rampage through nearby bars. (Photo by Luke MacGregor/Bloomberg)

A young boy plugs his ears as his sister (C) and nanny (L) watch from Gravelly Point Park as planes land at Reagan National Airport in Arlington, Virginia on June 29, 2017. President Donald Trump' s travel ban on people from six mostly Muslim countries will come into force late Thursday, as controversy swirls over who qualifies for an exemption based on family ties. (Photo by Jim Watson/AFP Photo)