Students training to be flight attendants hold books on their heads, chopsticks in their mouths, and papers in between their knees, as they take part in a standing posture practice at a vocational school in Shijiazhuang, Hebei province, China May 4, 2017. (Photo by Reuters/Stringer)

Festival goers having fun at the Balaton Sound music festival in Zamardi next to the Lake of Balaton, 110 km (68 miles) west of Budapest, July 8, 2017. (Photo by Sandor Csudai)

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)

A man impersonating Kim Jong-un gestures during the athletics at the Rio 2016 Olympic Games at the Olympic Stadium in Rio de Janeiro on August 18, 2016. (Photo by Johannes Eisele/AFP Photo)

In a handout picture released by the British Ministry of Defence via their Defence News Imagery website on August 22, 2016, Nils Olav the penguin inspects the Guard of Honour formed by His Majesty the King of Norway's Guard on August 22, 2016 at Edinburgh Zoo in Scotland. His Majesty the King of Norway's Guard paid a very special visit to RZSS Edinburgh Zoo to bestow a unique honour upon resident king penguin Sir Nils Olav. Already a knight, the most famous king penguin in the world was given the new title of “Brigadier Sir Nils Olav”. (Photo by Mark Owens/AFP Photo)

A woman offers a prayer at Pashupatinath Temple during the Teej festival in Kathmandu, Nepal September 4, 2016. During this festival, married Hindu women observe day-long fast and pray for a happy married life while those unmarried pray for a good husband. (Photo by Navesh Chitrakar/Reuters)

American Yoga teacher Dashama poses on a Yoga-board during a preview of the 46th International Boat Fair in Duesseldorf January 16, 2015. The BOOT 2015 watersports fair, with more than 1,600 international exhibitors will run in Duesseldorf from January 17 to January 25. (Photo by Ina Fassbender/Reuters)

A Sri Lankan elephant, accompanied by his mahout, browse through a roadside fruit stall in Colombo on January 19, 2015. The Sri Lankan elephant is listed as endangered by the International Union for Conservation of Nature (IUCN) as the population has declined by at least 50 percent over the last three generations, with the species threatened by habitat loss, degradation and fragmentation. (Photo by Lakruwan Wanniarachchi/AFP Photo)