A reveller is photographed during a traditional Maracatu carnival in Olinda, Brazil February 8, 2016. (Photo by Ueslei Marcelino/Reuters)

Employees cover bacon on fried dranik, a potato pancake that is the national dish of Belarus, in the Sula History Park near the village of Sula, Belarus March 7, 2016. According to the park's representatives, the two-metre-wide pancake was an attempt to enter the Guinness World Records as the world's largest dranik. (Photo by Vasily Fedosenko/Reuters)

A girl reacts as she receives polio vaccine drops during a house-to-house vaccination campaign in Yemen's capital Sanaa, November 10, 2015. (Photo by Khaled Abdullah/Reuters)

German KUKA Robotics' robot LBR iiwa demonstrates a flower arrangement at the International Robot exhibition in Tokyo, Wednesday, December 2, 2015. (Photo by Shizuo Kambayashi/AP Photo)

Newly-wed couples attend their group wedding ceremony which was held as part of the Harbin International Ice and Snow Festival in the northern city of Harbin, Heilongjiang province January 6, 2016. As many as 15 couples attend this mass wedding ceremony. (Photo by Aly Song/Reuters)

Michael O’Neill won a prize in animal portraits with fry of a peacock bass hovering around their mother for protection against predators in South Florida. (Photo by Michael Patrick O'Neill/2016 National Geographic Nature Photographer of the Year)

A female motorcycle cop directs traffic wearing crash helmet, Haywarket Square, Boston, Massachusetts, 1979. (Photo by Spencer Grant/Getty Images)

Buns are stamped the Chinese characters “Ping An”, meaning peaceful and safe, inside a bakery, at Hong Kong's Cheung Chau island, China May 17, 2015, ahead of the upcoming Bun Festival on May 25. The festival celebrates the islanders' deliverance from famine many centuries ago and is meant to placate ghosts and restless spirits. (Photo by Tyrone Siu/Reuters)