A leg of a “diablito” frog (Oophaga sylvatica) is photographed in a laboratory at a laboratory in the zoo of Cali, Colombia, on July 19, 2019. Colombia is the second country with the largest number of amphibians in the world after Brazil. More than 40% of amphibian species worldwide are in danger of extinction. (Photo by Luis Robayo/AFP Photo)

A dancer poses for a photograph as part of the “Dance as Art” photo project in Times Square in New York, on September 22, 2014. (Photo by Carlo Allegri/Reuters)

A pornographer posing as a fashion photographer sets up a photoshoot with an unsuspecting model, in the hope of getting some illicit footage. He suggests she try wearing something a little more suggestive. (Photo by Pryor/Three Lions/Getty Images). Circa 1955

A street cleaner demonstrates his martial arts skills in front of a closed shop near Beijing's Tiananmen Square September 2, 2015 as the capital prepares for tomorrow's parade. (Photo by Damir Sagolj/Reuters)

Brett Throckmorten of Barnes Bullets shows Logan Wingo how to sight down an electronic rifle in the trade booth area during the National Rifle Association's annual meeting in Nashville, Tennessee, April 11, 2015. (Photo by Harrison McClary/Reuters)

A female Chinese People's Liberation Army soldier looks at members of an honor guard preparing for a welcome ceremony for visiting German President Joachim Gauck, outside the Great Hall of the People in Beijing, Monday, March 21, 2016. (Photo by Andy Wong/AP Photo)

Chinelos (traditional costumed dancers) perform in front of San Andres Ocotlan church as part of continuing festivities to welcome the new year in Calimaya, Mexico on January 4, 2016. (Photo by Arturo Hernandez/Demotix/Corbis)

Chinese hostesses, who serve the delegates of the Chinese People's Political Consultative Conference and National People's Congress, have souvenir photos taken in front of the Great Hall of the People during sessions of the CPPCC and NPC held in Beijing, China Tuesday, March 4, 2014. (Photo by Andy Wong/AP Photo)