In this Monday, January 18, 2016 photo, Iranian rock climber, Farnaz Esmaeilzadeh, scales a climbing gym in the city of Zanjan, some 330 kilometers (207 miles) west of the capital Tehran, Iran. Esmaeilzadeh, 27, who has been climbing since she was 13, has distinguished herself in international competitions despite the barriers she faces as a female athlete in conservative Iran. (Photo by Ebrahim Noroozi/AP Photo)

Dogs, Pretty, Llilly, and Rocky wait for their turn to be examined by veterinarians during a community campaign for the sterilisation and deworming of dogs and cats in Havana, Cuba February 25, 2016. (Photo by Reuters/Stringer)

Female Kurdish Peshmerga take part their graduation ceremony at a police academy in Zakho district of the Dohuk Governorate of the Iraqi Kurdistan province, Iraq March 30, 2016. (Photo by Ari Jalal/Reuters)

The world-famous sprinter Usain Bolt, 30, took a break from the track to celebrate Carnival as revellers doused each other with paint in Trinidad and Tobago on February 26, 2017. (Photo by David Wears/Splash News and Pictures)

A Palestinian man rides his horse on a beach in Gaza City February 17, 2017. (Photo by Mohammed Salem/Reuters)

Cake made by Gisela Prekau on display at the Cake International show at Alexandra Palace in London, UK on April 22, 2017. Cake International 2017, the Cake Decorating and Baking Show, takes place over the weekend at Alexandra Palace, North London featuring giant cakes, moving cakes, stunning crafter cakes, exquisitely detailed cakes and the latest ranges of cake decorating products and accessories, college displays and workshops. (Photo by Dinendra Haria/Rex Features/Shutterstock)

Pamukkale, Turkey, is home to these terrace pools, formed by the build-up of carbonate mineral from the warm water flowing from the thermal springs above. (Photo by Image Courtesy of Jennifer Hayes/Getty Images)

Revellers take part in the annual Gay Pride parade along Paulista Avenue in Sao Paulo, Brazil, May 29, 2016. (Photo by Nacho Doce/Reuters)