An opposition supporter gestures with a knife during clashes with police in Kibera slum in Nairobi, Kenya on October 26, 2017. Kenyans trickled into polling stations today for a repeat election that has polarised the nation, amid sporadic clashes as supporters of opposition leader ignored his call to stay away and tried to block voting. (Photo by Goran Tomasevic/Reuters)

Firefighters carry a woman on a stretcher after a car drove into the crowded seaside boardwalk along Copacabana beach in Rio de Janeiro, Brazil, Thursday, January 18, 2018. Military police said on Twitter that at least 11 people were injured and that the driver has been taken into custody. (Photo by Silvia Izquierdo/AP Photo)

South Vietnamese forces escort suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street February 1, 1968, early in the Tet Offensive. Moments later, Lem was executed by Gen. Nguyen Ngoc Loan, chief of the national police. (Photo by Eddie Adams/AP Photo)

A Venezuelan Bolivarian National Police officer fires tear gas towards demonstrators during a protest in Caracas, Venezuela, Monday, April 10, 2017. Thousands of people in Venezuela's capital are protesting against the government of President Nicolas Maduro, demanding new elections and vowing to stay in the streets during the usually quiet Easter Week. (Photo by Fernando Llano/AP Photo)

Demonstrators clash with members of the Bolivarian National Police as protests continue in Caracas, Venezuela, 20 April 2017. The Bolivarian National Guard, using tear gas, tried to disperse protests against the government of Venezuelan President Nicolas Maduro. (Photo by Miguel Gutierrez/EPA)

Ukrainian police detain activists of women's rights group Femen as they protest against homophobia outside the parliament building in Kiev, Ukraine, November 12, 2015. Femen and gay rights activists are pushing parliament to adopt bills, including one that would ban discrimination in the workplace based on sexuality, which is included in a package of laws to liberalise Ukraine's visa regime with the EU. (Photo by Gleb Garanich/Reuters)

A doll, placed by stranded Iranian migrant protesters, hangs from barbed wire in front of Madedonian police at the Greek-Macedonian border near to the Greek village of Idomeni November 29, 2015. The protesters were demonstrating against what they say is the closure of the border for Iranian migrants. According to the demonstrators, the hanging toys and dolls represent the outcome of being unable to return, if they are sent back to Iran. (Photo by Yannis Behrakis/Reuters)

Germany's Wolfgang Kimmig-Liebe, who has been volunteering as Santa Claus for years, is searched by a Carabiniere paramilitary police officer before entering in St. Peter's Square at the Vatican to attend Pope Francis general audience, Wednesday, December 2, 2015. (Photo by Alessandra Tarantino/AP Photo)