A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Young Korean women wearing hanbok (Korean traditional dress) walk inside Gyeongbok Palace on March 27, 2016 in Seoul, South Korea. There has been a trend in recent years for the young Koreans to wear the traditional Korean dress, Hanbok. Wearing the traditional dress, they will walk around downtown Seoul on weekends taking selfies, and share their memories with friends on social media, and also to promote their traditional dress to foreign visitors. (Photo by Jean Chung/Getty Images)

A man prepares plastic strings, used to produce mats, inside a mat factory in the rebel-controlled area of Maarshureen town in Idlib province, Syria, December 22, 2015. The town is known for the significant number of mat factories which exports its production mainly to nearby Iraq through checkpoints controlled by insurgents. But in the past months the business has declined due to heavy airstrikes against insurgents, vendors said. (Photo by Khalil Ashawi/Reuters)

Police officers escort people from inside the shopping center as they respond to a shooting at the Olympia Einkaufzentrum (OEZ) at July 22, 2016 in Munich, Germany. According to reports, several people have been killed and an unknown number injured in a shooting at a shopping centre in the north-western Moosach district in Munich. Police are hunting the attacker or attackers who are thought to be still at large. (Photo by Joerg Koch/Getty Images)

One-year-old female giant panda cub Nuan Nuan reacts inside her enclosure during joint birthday celebrations for the panda and its ten-year-old mother Liang Liang at the National Zoo in Kuala Lumpur on August 23, 2016. Giant pandas Liang Liang, aged 10, and her Malaysian-born cub Nuan Nuan, 1, were born on August 23, 2006 and August 18, 2015 respectivetly. (Photo by Mohd Rasfan/AFP Photo)

Trainees of the Tianjiao Special Guard/Security Consultant bodyguard training camp watch their instructor use a scarf to cover a student's head during a demonstration of close-quarter combat skills at a special course on flight safety inside a scale model of a passenger jet at a flight attendant training centre on the outskirts of Beijing, March 18, 2014. Inspired by the missing Malaysia Airlines Flight MH370, the company wanted to emphasize the importance of aviation safety by teaching their trainees emergency evacuation procedures and close-quarter combat skills to handle situations such as natural disasters and plane hijacks, according to the company. (Photo by Jason Lee/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)

The figure of an eight-year-old boy is seen inside a suitcase on a Spanish civil guard scanner screen at the border between Morocco and Spain's north african enclave Ceuta, Spain in this handout photo released May 8, 2015. A 19-year-old woman was arrested May 7, 2015 for the attempted smuggling of the boy, who was checked by medics and handed over to juvenile prosecutors office, according to authorities. (Photo by Reuters/Ministerio Del Interior)