General view during the Gucci event during Milan Fashion Week Fall/Winter 2017/18 on February 22, 2017 in Milan, Italy. (Photo by Vittorio Zunino Celotto/Getty Images for Gucci)

Revelers dance at the Old Settler's Music Festival in Driftwood, Texas, U.S. on April 22, 2017. (Photo by Mohammad Khursheed/Reuters)

Musicians of the alphorn band "Holdersberger Alp- Traum- Blaeser" perform their skills on a raft floating on the Elbsee lake near Aitrang, southern Germany, on June 11, 2017. (Photo by Karl-Josef Hildenbrand/AFP Photo/DPA)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on June 30, 2017. (Photo by Sandor Csudai/Rockstar Photographers)

Artist Le Pustra and organiser Else Edelstahl pose for a picture at Simon Dach Strasse, a street filled with many bars, in Berlin, Germany, August 28, 2016. Else Edelstahl organises the party series “Boheme Sauvage”, in which people dress up in 1920s style, celebrating Berlin nightlife of a past era. (Photo by Hannibal Hanschke/Reuters)

Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

A walrus kisses a visitor during a sea animal show at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, southwest of Tokyo, Monday, September 11, 2017. (Photo by Shizuo Kambayashi/AP Photo)

Leonhard Nienbling is shown with his 6-month old pet baboon Jackl, who holds a 6-month old kitten, its playmate, June 29, 1952. Niebling has quite an animal collection at his home in Zirndorf, Germany. (Photo by Heinrich Sanden/AP Photo)