Visitors look at graffiti art created by Brazilian artist Image during the 3rd annual Graffiti Fine Art Biennial International exhibit, at the Pavilion of Brazilian Cultures, in Sao Paulo, Brazil, Tuesday, April 21, 2015. The month-long event features the work of more than 60 street artists, representing 11 countries. (Photo by Andre Penner/AP Photo)

A white Bengal tiger cub plays with its mother in a zoo in the Siberian city of Novosibirsk, about 2,800 kilometers (1,750 miles) east of Moscow, Russia, Tuesday, April 21, 2015. Two blue-eyed Bengal tiger cubs were born in March to a couple of white tigers at Novosibirsk zoo. (Photo by Ilnar Salakhiev/AP Photo)

Members of the Barrio 18 gang run upon their arrival to the San Francisco Gotera penitentiary April 21, 2015. The Salvadoran goverment transfered 1,177 inmates, members of the Barrio 18 gang from Izalco jail to San Francisco Gotera in a effort to curb gang violence activity, according to local media. (Photo by Jose Cabezas/Reuters)

Siberian Huskies pull a contestant during the “Kara-Dag 2016” open amateur dog sled and skijoring race near the village of Yelovoye in Taiga district, outside Krasnoyarsk, Siberia, Russia, February 21, 2016. Dogs and their owners from various regions of Siberia took part in an annual race. (Photo by Ilya Naymushin/Reuters)

A military band prepares to play the national anthems before Cuban President Raul Castro welcomes U.S. President Barack Obama at the Palacio de la Revolucion in Havana March 21, 2016. Barack Obama on Sunday became the first US president in 88 years to visit Cuba, touching down in Havana for a landmark trip aimed at ending decades of Cold War animosity. (Photo by Jonathan Ernst/Reuters)

A man shows the logo of a T-shirt that reads “Stop the Cut” referring to Female Genital Mutilation (FGM) during a social event advocating against harmful practices such as FGM at the Imbirikani Girls High School in Imbirikani, Kenya, April 21, 2016. (Photo by Siegfried Modola/Reuters)

Julya Baer, 30, attends a candlelight vigil and celebration of Prince's life in Leimert Park in memory of musician Prince on April 21, 2016, in Los Angeles, California. Prince died earlier today at his Paisley Park compound at the age of 57. (Photo by Kevork Djansezian/Getty Images)

Afghan paraglider Leeda Ozori, 21, walks after practicing in Kabul, Afghanistan September 14, 2015. She is one of a group of young Afghans taking to the skies of a capital where military helicopters and surveillance balloons are a far more familiar sight. Women in Afghanistan's conservative Muslim society are increasingly entering areas such as education, sports and the workplace, but most still wear the head-to-toe garment, the burqa. (Photo by Mohammad Ismail/Reuters)