Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

A crocodile at a zoo in the southern Taiwan city of Kaohsiung holds the forearm of a zoo veterinarian in its teeth, April 2007. Surgeons in Taiwan have reattached a vet's arm, after it was bitten off by a crocodile as he tried to give it an anaesthetic injection. His attacker is one of a pair of Nile crocodiles kept at Shoushan zoo. Nile crocodiles are known to be man-eaters, but are also listed as an endangered species. (Photo by Frank Lin/Reuters)

Children residents take a selfie as they wait for the police to dance, an unconventional approach to connect the police with the community in rough neighbourhoods, as part of the “Tirando Barrio” (Marking territory) programme in Saltillo, Northern Mexico September 9, 2016. T-Shirt reads “Street Dancers”. (Photo by Daniel Becerril/Reuters)

Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)

Brazilian model and actress Alessandra Ambrosio seen wearing a Gucci fanny pack and boots from Dior on April 15, 2018 in Indio, California. (Photo by Timur Emek/GC Images)

Actor Candis Cayne performs at John Varvatos + OUT Support the Gay Men's Chorus of LA on September 29, 2016 in Los Angeles, California. (Photo by Matt Winkelmeyer/Getty Images for John Varvatos)

An airplane is silhouetted at sunrise, seen from the suburb of Saint-Cloud, near Paris, France, 08 December 2016. Paris is undergoing a third day pollution spike, prompting the city to limit vehicle circulation. (Photo by Ian Langsdon/EPA)

People wearing Christmas hats bath in a pool of watermelon peel during a Christmas service at a hot spring in Luoyang, Henan province, China, December 24, 2016. (Photo by Reuters/Stringer)