A Hong Kong Correctional Services Dog Unit (CSDU) officer demonstrates training at the CSDU training facility in Stanley, Hong Kong, China, 27 February 2018. The Hong Kong CSDU consists of 29 staff members divided across six dog teams. According to the department's latest figure from 2017, the average daily penal population of Hong Kong was 8,529. (Photo by Jérôme Favre/EPA/EFE)

Technical staff take shelter as a helicopter takes off prior to the Nendaz Freeride skiing and snowboard competition, a Freeride World Tour Qualifier (FWQ) event, on the Mont Gond in Nendaz, Switzerland on March 21, 2018. (Photo by Valentin Flauraud/EPA/EFE/Rex Features/Shutterstock)

A policewoman reacts as she falls off from a motorcycle while taking part in a rehearsal for Independence Day celebrations, in Ahmedabad, India August 4, 2017. (Photo by Amit Dave/Reuters)

Graduates jump as they pose for photographs in front of the Tiananmen Gate and the giant portrait of late Chinese Chairman Mao Zedong, on the Tiananmen Square in Beijing, June 19, 2014. (Photo by Reuters/Stringer)

A woman poses for a photograph in front of a 3D painting at HK 3D Museum in Hong Kong June 26, 2014. (Photo by Tyrone Siu/Reuters)

A riot policeman uses a baton to hit a rioting University of Nairobi student in Kenya's capital Nairobi, in this May 20, 2014 file photo. (Photo by Noor Khamis/Reuters)

Human canvases modelling world famous artworks including Van Gogh's Sunflowers and Edvard Munch's The Scream take to the streets of London in a bid to mend Britain's disconnect with art on September 25, 2017. Award winning body paint artist Sarah Attwell was commissioned by online art platform Rise Art to show that great art is for everybody, following research that revealed 1 in 6 Brits have never set foot in an art gallery. (Photo by Imagewise Ltd/Rex Features/Shutterstock)

A woman stumbes as people run down Oxford Street, London, Britain, November 24, 2017. Police are responding to reports of an incident at London's Oxford Circus Tube station and have urged the public to avoid the area. (Photo by Peter Nicholls/Reuters)