Visitors observe the sculpture “That Girl” by U.S. artist Paul McCarthy, at the Hyperrealist Sculpture 1973-2016 exhibition in the Museum of Bellas Artes in Bilbao, northern Spain, July 27, 2016. (Photo by Vincent West/Reuters)

Joe Deedon, president of TAC ONE Consulting, demonstrates searching for a shooter in a middle school during an Active Shooter Response course offered by TAC ONE in Denver April 2, 2016. According to TAC ONE, the course, which is offered for the first time to concealed weapons permit carrying civilians, is designed at preparing people to effectively save lives prior to the arrival of law enforcement at an active shooter incident. (Photo by Rick Wilking/Reuters)

A Cavalier King Charles Spaniel competes in the Masters Agility Championship Finals competition during the 141st Westminster Kennel Club Dog Show in New York City, U.S. February 11, 2017. (Photo by Brendan McDermid/Reuters)

A boy sits on the back of a crocodile on May 19, 2018 at a pond in Bazoule in Burkina Faso, a village which happily shares its local pond with “sacred” crocodiles. Crocodiles may be one of the deadliest hunters in the animal kingdom, but in a small village in Burkina Faso it is not unusual to see someone sitting atop one of the fearsome reptiles. According to local legend, the startling relationship with the predators dates back to at least the 15 th century. The village was in the grip of an agonising drought until the crocodiles led women to a hidden pond where the population could slake their thirst. (Photo by Olympia de Maismont/AFP Photo)

Camels graze in front of a spacecraft tracking station ahead of the Soyuz MS-10 upcoming launch at the Baikonur Cosmodrome, Kazakhstan, October 9, 2018. (Photo by Shamil Zhumatov/Reuters)

A cat and a seagull feeding on a street in Heybeliada, the second largest of the Prince Islands in the Sea of Marmara, near Istanbul, Turkey on February 01, 2017. (Photo by Sebnem Coskun/Anadolu Agency/Getty Images)

Ford displays the drive train of the F150 Raptor SVT truck during the media preview of the Chicago Auto Show at McCormick Place on February 8, 2012 in Chicago, Illinois. The show, which is the largest and oldest auto show in the country, opens to the public on February 10. (Photo by Scott Olson/Getty Images)

Audrey Hepburn cooking at home, 1954. Colorized by Dana Keller.