Gunfire was brought to the steps of President Truman's Washington home, Blair House, as two assassins tried to kill the chief executive, November 1, 1950. One of the gunmen, Oscar Collazzo of New York, lay wounded at the bottom of Blair House's front steps after the president's police guard had finished their work, at the cost of one guards' life, Dec. 9, 1950. The second gunman was killed. (Photo by Harvey Georges/AP Photo)

A girl cools off from the heat in water from an open fire hydrant in the Washington Heights section of upper Manhattan in New York City, New York, U.S., July 19, 2019. (Photo by Mike Segar/Reuters)

East Berliners crossing into the West Berlin on November 11, 1989 at the Potsdamer Platz, Germany. (Photo by Kai Wiedenhoefer)

An artwork entitled “Are you still mad at me?” by John Isaacs is displayed at the Death: A Self-portrait exhibition at the Wellcome Collection on November 14, 2012 in London, England. The exhibition showcases 300 works from a unique collection by Richard Harris, a former antique print dealer from Chicago, devoted to the iconography of death. The display highlights art works, historical artifacts, anatomical illustrations and ephemera from around the world and opens on November 15, 2012 until February 24, 2013. (Photo by Peter Macdiarmid)

Hair artist and barber Nariko, 27, etches an image of Barcelona's Neymar on the head of customer Luiz Fernadez, 15, before the Champions League semifinal first leg soccer match between Barcelona and Bayern Munich, at his barbershop in Sao Vicente, near Santos, in Sao Paulo state May 6, 2015. Nariko, who was motivated to get into the profession by his grandfather and uncle, has been etching profiles of the famous onto the sides and backs of heads for about a year or so. (Photo by Nacho Doce/Reuters)

A member of security personnel stands on duty on an empty train platform inside a station on the Subway Line Number 1 on the eve of the Chinese Lunar New Year, in Beijing, China, February 7, 2016. According to local media, traffic in Beijing has seen a rare relief from its usual heavy pressure after 15 million people have left the city, heading for family reunions in their hometowns on the eve of the Chinese Lunar New Year of Monkey. (Photo by Jason Lee/Reuters)

A protester gestures after he saw a dead protester in Kampala, Uganda February 15, 2016. At least one person has been killed in Uganda's capital Kampala as police clashed with opposition supporters after briefly detaining a top presidential candidate twice as he tried to hold campaign rallies days before a general election. Several people were wounded in the clashes as police fired bullets and tear gas while opposition supporters hurled rocks and erected street barricades in the capital's Wandegeya suburb, witnesses said according to a Reuters news agency report. (Photo by Goran Tomasevic/Reuters)

Five-year-old Ghazal al-Hussein poses inside a classroom in the rebel-controlled area of Maarshureen village in Idlib province, Syria March 12, 2016. March 15 marks the 5th anniversary of peaceful protests against Syria's President Bashar al-Assad, leading to the devastating civil conflict in the country. These are portraits of five-year-old Syrian children who have only known conflict in their country. (Photo by Khalil Ashawi/Reuters)