A visitor looks at a sculpture by a Chinese artist Chen Wenling at the "Sculpture by the Sea" exhibition which runs along the Bondi to Tamarama coastal walk in Sydney on October 22, 2015. The world's largest annual free-to-the-public outdoor sculpture exhibition runs from October 22 – November 8 this year and features over 107 sculptures by artists around the world. (Photo by Saeed Khan/AFP Photo)

Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

A visitor walks past an installation artwork entitled “Confuciuse” which combines the word “Confucius” and “confuse” in the contemporary art exhibition at “Fun and Art” Festival on December 13, 2008 in Xian of Shaanxi Province, China. (Photo by China Photos/Getty Images)

Artwork by Ruth Bellotti & Steve Rosewell called “Soldier Scale 1:1” is seen at the 2008 Sculpture by the Sea launch at Mark's Park, Bondi on October 15, 2008 in Sydney, Australia. (Photo by Gaye Gerard/Getty Images)

A roadside currency exchange vendor sorts Indian currency notes at his stall in Agartala, India, December 6, 2016. (Photo by Jayanta Dey/Reuters)

A labourer pulls a cart loaded with sacks of spices at a wholesale spice and chemical market in the old quarters of Delhi, India, December 19, 2016. Picture taken December 19, 2016. (Photo by Adnan Abidi/Reuters)

A hillside erupts in flame as a raging wildfire fire burns in Placerita Canyon in Santa Clarita, Calif., Monday, July 25, 2016. A raging wildfire that forced thousands from their homes on the edge of Los Angeles continued to burn out of control Monday as frustrated fire officials said residents reluctant to heed evacuation orders made conditions more dangerous and destructive for their neighbors. (Photo by Nick Ut/AP Photo)

Vets of Animals Asia Foundation's Vietnam Bear Rescue Center hold a paw of a sun bear as they check its health while it is rescued from a Vietnamese family in Nam Dinh province, south of Hanoi, Vietnam August 18, 2016. A man in northern Vietnam has voluntarily handed over a bear his family had caged for seven years to an animal rights organization, which will take it to a nearby sanctuary. (Photo by Reuters/Kham)