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)

A workman walks past a large mural on the side of a building during the “Sand Sea & Spray” Urban Art Festival in Blackpool, north west England on July 11, 2015. (Photo by Oli Scarff/AFP Photo)

A model poses backstage ahead of the NLP show at Mercedes-Benz Fashion Week Australia 2014 at Carriageworks on April 7, 2014 in Sydney, Australia. (Photo by Brendon Thorne/Getty Images)

Netapp Endura team rider Slovenian Blaz Jarc (R) crashes into Katusha team rider Russian Viacheslav Kuznetsov (ground) during the 112th Paris Roubaix cycling race, in Roubaix, France, 13 April 2014. (Photo by Nicolas Bouvy/EPA)

Promotional models use their smartphones during their break at the Global Mobile Internet Conference in Beijing May 6, 2014. Mobile Internet industry executives, developers and investors from more than 30 countries took part in the Global Mobile Internet Conference in Beijing, the organiser said. (Photo by Kim Kyung-Hoon/Reuters)

British singer and songwriter Charlotte Emma Aitchison aka Charli XCX poses in the green room for a portrait before the Sonos And Pandora Present “An Evening With Charli XCX” event at Sonos Studio on June 10, 2014 in Los Angeles, California. (Photo by Joe Scarnici/Getty Images for Sonos)

A Brazil fan enjoys the atmosphere prior to the 2014 FIFA World Cup Brazil Semi Final match between Brazil and Germany at Estadio Mineirao in Belo Horizonte, Brazil, on Jule 8, 2014. (Photo by Robert Cianflone/Getty Images)

A 41-year-old man going by the name of Chibatman rides his “Chibatpod” on the road in Chiba, east of Tokyo, August 31, 2014. The man, who dresses up as the comic book superhero Batman, came up with his moniker after adding a prefix of the first three letters of the city name, of which he roams on his three-wheeled motorcycle. However, unlike the hero from the Batman series, he rides around in his machine, designed from inspiration of the “Batpod” from the movies The Dark Knight and The Dark Knight Rises, delivering smiles instead of fighting crime. (Photo by Yuya Shino/Reuters)