A three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)

Anti-government protesters react on the grounds of the Mezhyhirya residence of Ukraine's President Viktor Yanukovich in the village Novi Petrivtsi, outside Kiev February 22, 2014. (Photo by Konstantin Chernichkin/Reuters)

Karis, an eleven week old lion cub, plays in fallen leaves brushed up by keepers in her enclosure at Blair Drummond Safari Park, near Stirling, Scotland, on November 20, 2013. (Photo by Andrew Milligan/PA Wire)

“DC3 Wreck”. A capture of a US military DC3 plane wreck at the southern black beach in Iceland. Photo location: Iceland. (Photo and caption by Naian Feng/National Geographic Photo Contest)

Soniya, 6, whose family moved to Islamabad from Pakistan's Khyber-Pakhtunkhwa province to look for work, stands outside their house on the outskirts of Islamabad January 1, 2015. (Photo by Zohra Bensemra/Reuters)

Pupils of the Dao ethnic tribe return home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

Two working girls entertaining themselves in the absence of customers at the Moonlite Bunny Ranch, a legal brothel owned by Dennis Hof, in Lyon County, one of the fews counties in the USA which permits legalized prostitution. (Photo by Stephan Gladieu/Getty Images)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on June 26, 2017. (Photo by Mudra László/Rockstar Photographers)