A pro-democracy demonstrator fights with a Soviet soldier on top of a tank parked in front of the Russian Federation building on August 19, 1991, after a coup toppled Soviet President Mikhail Gorbachev. The same day, thousands in Moscow, Leningrad, and other cities answered Russian Republic President Boris Yeltsin's call to raise barricades against tanks and troops. (Dima Tanin/AFP/Getty Images)

An injured young woman is led away after an incident at Parsons Green underground tube station in west London on September 15, 2017. Police and ambulance services said they were responding to an “incident” at Parsons Green underground station in west London on Friday, following media reports of an explosion. A Metro. co. uk reporter at the scene was quoted by the paper as saying that a white container exploded on the train and passengers had suffered facial burns. (Photo by Luke MacGregor/Reuters)

Policemen detain topless activists of women's rights group Femen, who stage a performance during a protest against Ukrainian President Petro Poroshenko and the government while marking the Day of Dignity and Freedom near the presidential administration headquarters in Kiev, Ukraine November 21, 2017. (Photo by Valentyn Ogirenko/Reuters)

A man takes a photo as a puff of smoke comes from Mount Agung volcano, taken from the Rendang sub-district in Karangasem Regency on Indonesia's resort island of Bali on November 23, 2017. Thousands living in the shadow of the rumbling volcano on Indonesia's resort island of Bali fled on November 22 as fears grow that it could erupt for the first time in more than 50 years. (Photo by Sonny Tumbelaka/AFP Photo)

A dancer warms up backstage before the final of the 46th Prix de Lausanne, in Lausanne, Switzerland, 03 February 2018. Launched in 1973, the Prix de Lausanne is an international dance competition for young dancers aged 15 to 18. Closing the six-day event, prizes are awarded to the best of 21 finalists consisting of scholarships granting free tuition in a world-renowned dance school or dance company. (Photo by Valentin Flauraud/EPA/EFE)

Trainer Lawney Hill poses for a photograph as she wears tights over her face to keep out the cold after taking her horses out on the all-weather gallops in Tetsworth, Britain, March 2, 2018. (Photo by Eddie Keogh/Reuters)

Dancers wait at backstage as they prepare for a dance performance during the Bali Arts Festival in Bali, Indonesia, Wednesday, June 21, 2017. The resort island of Bali is holding a month-long annual Bali Arts Festival from June 10 to July 8. (Photo by Firdia Lisnawati/AP Photo)

A child sleeps under a table at the Jorkpan market in Sinkor district in Monrovia, Liberia on May 2, 2016. (Photo by Marco Longari/AFP Photo)