Sri Lankan participants control their bulls during a traditional cart race to mark the Sri Lanka National New Year in Homagama near Colombo on April 23, 2017. The new year marked by both the majority Sinhalese and minority Tamil population fell on April 14. (Photo by Lakruwan Wanniarachchi/AFP Photo)

A guard stands at Dityatki checkpoint, marking a 30 km (18-mile) zone around the Chernobyl nuclear power plant April 23, 2013. Ukraine will mark the 27th anniversary of the Chernobyl disaster, the world's worst civil nuclear accident, on April 26. (Photo by Gleb Garanich/Reuters)

Chinese artists perform on stage during the opening ceremony of the International Horticultural Exposition 2011 at the Exposition Park on April 28, 2011 in Xi'an, Shaanxi Province of China. The World Horticultural Exposition 2011 will be held in Xi'an from April 28 to October 22. (Photo by ChinaFotoPress/Getty Images)

A costumed guest attends WonderCon Anaheim 2015 at Anaheim Convention Center on April 4, 2015 in Anaheim, California. (Photo by Araya Diaz/WireImage)

A man rides a horse at a playground on a hill in Kabul April 19, 2015. (Photo by Mohammad Ismail/Reuters)

A dancer performs as visitors take pictures at an auto show in Tianjin, China April 28, 2016. (Photo by Reuters/Stringer)

Cosplayers attend Day 3 of WonderCon 2017 at Anaheim Convention Center on April 2, 2017 in Anaheim, California. (Photo by Justin Baker/FilmMagic)

Members of a propaganda troupe perform in a public square in Pyongyang on April 12, 2017. (Photo by Ed Jones/AFP Photo)