Wang uses a mobile phone as she take a rest in her room at the accommodation where patients and their family members stay while seeking medical treatments in Beijing, China, June 23, 2016. Wang, who suffers from cervical cancer, came from Inner Mongolia to seek treatment at a specialist hospital in Beijing. (Photo by Kim Kyung-Hoon/Reuters)

A man holds up for a picture a one hundred trillion Zimbabwean dollars note inside a shop in Harare, Zimbawe, June 12, 2015. Hyperinflation in Zimbabwe was a period of currency instability that began in the late 1990s shortly after the confiscation of private farms from landowners, towards the end of Zimbabwean involvement in the Second Congo War. During the height of inflation from 2008 to 2009, it was difficult to measure Zimbabwe's hyperinflation because the government of Zimbabwe stopped filing official inflation statistics. However, Zimbabwe's peak month of inflation is estimated at 79.6 billion percent in mid-November 2008. (Photo by Philimon Bulawayo/Reuters)

A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

Immigrants from the West Indies at Victoria Station in London, 1956. (Photo by Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images)

United States' Inika McPherson prepares an attempt during the women' s high jump final during the World Athletics Championships in London Saturday, August 12, 2017. (Photo by Kai Pfaffenbach/Reuters)

Family members of a taxi driver offer prayer in front of their taxi during the Vishwakarma Puja or the festival of the Hindu deity of architecture and machinery in Kolkata, India, September 17, 2017. (Photo by Rupak De Chowdhuri/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)

People pause at a memorial set up for victims of a mass shooting in Las Vegas, Nev., on Tuesday, October 3, 2017. A gunman opened fire on an outdoor music concert on Sunday. It was the deadliest mass shooting in modern U.S. history, with dozens of people killed and hundreds injured, some by gunfire, some during the chaotic escape. (Photo by John Locher/AP Photo)