An Afghan policeman stands guard as smoke and flames rise from the site of a huge blast struck near the entrance of Kabul's international airport, in Kabul on August 10, 2015. A huge blast struck near the entrance of Kabul's international airport on August 10 during the peak lunchtime period, officials said, warning that heavy casualties were expected. “The explosion occurred at the first check point of Kabul airport”, said deputy Kabul police chief Sayed Gul Agha Rouhani. (Photo by Shah Marai/AFP Photo)

A hot air ball balloon floats past while people stand in line to climb the Pyramid of the Sun and welcome the spring equinox in the pre-hispanic city of Teotihuacan, on the outskirts of Mexico City, Mexico, March 20, 2016. Spring equinox in Teotihuacán is an annual event which takes place around the 20th and 21st of March at the pre-Hispanic site of Teotihuacán, Mexico. This event is mirrored by other similar events in other pre-Hispanic sites such as Chichén Itzá and Malinalco, Mexico State. (Photo by Edgard Garrido/Reuters)

Members of Japanese idol group Kamen Joshi (Masked Girls) pose for a photo after a rehearsal for a concert at their theatre in Tokyo's Akihabara district, Japan March 17, 2016. For countless girl and pop-idol bands in Japan, standing out from the crowd can be daunting, but one group – “Kamen Joshi” – seems to have found the answer by hiding behind masks. The Tokyo-based all female band has 18 members, split into three groups that perform across Japan and elsewhere in Asia. (Photo by Toru Hanai/Reuters)

A herdsman stands on the back of a grey bull during a ceremony of driving sheep from their winter habitat to their summer pasture in the puszta or Hungarian steppe of Hortobagy, 183 kms east of Budapest, Hungary, 23 April 2016. Sheep are traditionally driven to their summer pasture at around St. George's Day in the Hortobagy region, because livestock breeding people traditionally consider St. George's Day the beginning of spring. (Photo by Zsolt Czegledi/EPA)

A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)

Fresa, 5, stands inside the dog shelter “Santuario Milagros Caninos” on the outskirts of Mexico City August 29 2014. Fresa underwent reconstructive surgery after her previous owners hacked off half of her snout with a sharp object, possibly a machete, according to surgeon Jesus Paredes. After neighbours found Fresa wandering on the streets, they handed her over to a shelter where Paredes performed a three-hours intervention to enable her to breathe again through her nostrils, to remove her protruding jaw and reconstruct the lips with flaps of skin and mucous. (Photo by Edgard Garrido/Reuters)

Members of the U.S. Army 173rd Airborne Brigade stand at attention as a Ukrainian folk dance group performs at the opening ceremony of the “Rapid Trident” NATO military exercises on September 15, 2014 near Yavorov, Ukraine. The two-week exercises include participating units from a variety of NATO and NATO-associate countries as well as Ukrainian troops. Meanwhile fighting between pro-Russian separatists and Ukrainian armed foces has flared again in eastern Ukraine in a battle for the control of Donetsk airport despite the tenuous ceasefire. (Photo by Sean Gallup/Getty Images)

Britain's BASE jumper Sam Hardy lives up to his name after throwing himself off the top of the 335m-high Kuala Lumpur Tower during the KL Tower International Jump in Kuala Lumpur, Malaysia, Saturday, September 27, 2014. BASE stands for the places such jumpers usually jump from: buildings, antennas, spans (bridges) and earth (cliffs). (Photo by Lai Seng Sin/AP Photo)