People walk on a sightseeing platform in Zhangjiajie, Hunan Province, China, August 1, 2016. China has opened a 100-metre-long glass skywalk stretching around a cliff on the side of the Tianmen Mountain. The skywalk provides a view of a 300-metre drop and overlooks Tongtian Avenue, a mountain road with 99 turns that snakes up the mountain. When translated in English, it means “Avenue to the Sky”. (Photo by Reuters/Stringer)

Puerto Rico's Grace Claxton warms up before competing in the Women's 400m Hurdles Round 1 during the athletics event at the Rio 2016 Olympic Games at the Olympic Stadium in Rio de Janeiro on August 15, 2016. (Photo by Jewel Samad/AFP Photo)

A villager watches as Mount Sinabung volcano erupts, in Kuta Tengah village, Karo Regency in Indonesia's North Sumatra April 1, 2015. The Indonesian volcano was dormant for 400 years before erupting in 2010. (Photo by Y. T. Haryono/Reuters)

Anti-pollution protesters wearing traditional costumes and contemporary gas masks ride bicycles in the Qingming Grand river park in Kaifeng, Henan Province, China on January 1, 2017. The Beijing Municipal Environmental Protection Bureau extended an “orange alert” for heavy air pollution for three more days. (Photo by SIPA Asia/Rex Features/Shutterstock)

A combination of pictures shows people taking photos of themselves in Tiananmen Square as they celebrate National Day marking the 67th anniversary of the founding of the People's Republic of China, in Beijing October 1, 2016. (Photo by Damir Sagolj/Reuters)

A general view of atmosphere during 2016 New York Comic Con – Day 1 on October 6, 2016 in New York City. The annual event offers pop culture fans exhibitors and displays of popular video games, movies and comic books and many people attending dress as their favorite character. (Photo by Daniel Zuchnik/Getty Images)

A voodoo believer, dressed as "Gede", a spirit of voodoo, sits on the cross of Baron Samdi during celebrations at the cemetery of Port-au-Prince, Haiti, November 1, 2016. Voodoo believers and devotees offer candles, alcohol and food. The Day of the Dead is celebrated on the first two days of November during All Saints and All Souls Day. (Photo by Andres Martinez Casares/Reuters)

Members of the Oath Keepers and general public return fire during a simulated attack as they take part in a tactical training session in northern Idaho, U.S. October 1, 2016. In April 2015 Reuters photographer Jim Urquhart was assigned to cover the Oath Keepers during a tour of the Sugar Pine gold mine in Oregon after the group of former cops, military, firefighters and other first responders had risen to prominence during a standoff in Nevada over land rights. (Photo by Jim Urquhart/Reuters)