Animal rights activists perform, demanding the abolition of bullfights, during a demonstration in Medellin, Colombia February 11, 2018. The Colombian Constitutional Court overruled on February 7, 2018, a judgment that allowed to hold a referendum regarding bullfights. (Photo by Fredy Builes/Reuters)

Female members of police commando march during a ceremony on International Women's Day, at the police headquarters in Islamabad, Pakistan March 8, 2018. (Photo by Faisal Mahmood/Reuters)

British theoretical physicist Stephen Hawking, Cambridge University Professor and Fellow, circa 1985. Stephen Hawking, the brightest star in the firmament of science, whose insights shaped modern cosmology and inspired global audiences in the millions, has died aged 76. (Photo by Gemma Levine/Getty Images)

An Afghan boy jumps off the turret of a Soviet tank on a hilltop on the the outskirts of Kabul, Sunday, March, 4, 2018. (Photo by Rahmat Gul/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)

An artists performs on the street during a Myfest festival marking the May Day in the Kreuzberg district in Berlin, Germany on May 1, 2018. (Photo by Fabrizio Bensch/Reuters)

Angel Hall, 22, (C) and Bri Artis, 21, (R) dance in a silent disco on the fourth and final day of the Firefly Music Festival in Dover, Delaware on June 17, 2018. (Photo by Mark Makela/Reuters)

A rickshaw puller transports passengers through a water-logged street after heavy rain in Kolkata, India on June 26, 2018. (Photo by Rupak De Chowdhuri/Reuters)