In this photo taken on Friday, July 14, 2017, a student at a paramilitary camp for children calls the rank to attention outside Kiev, Ukraine. As the deadly conflict in eastern Ukraine entered its third year, some parents in Ukraine are anxious to make sure their children are ready to fight it, instead of swimming and playing volleyball. (Photo by Efrem Lukatsky/AP Photo)

The battle by Jose Garcia, US. Category: bird behaviour. A great white heron (Ardea herodias occidentalis) fighting a green snake in the Florida Everglades. The fight lasted for nearly 20 minutes with the heron having to release its prey. (Photo by Jose Garcia/2017 Bird Photographer of the Year Awards)

Soyuz MS-12 spacecraft with crew members of Expedition 59/60 Russian cosmonaut Alexey Ovchinin, NASA astronauts Christina Koch and Nick Hague lifts off from the launch pad at the Russian leased Baikonur cosmodrome, Kazakhstan, 15 March 2019. Hague, Koch, and Ovchinin will spend six-and-a-half months living and working aboard the International Space Station. (Photo by Sergei Ilnitsky/EPA/EFE)

Sukhoi Su-30SM jet fighters of the Russkiye Vityazi (Russian Knights) aerobatic team perform during a demonstration flight in Krasnoyarsk, Russia October 6, 2018. (Photo by Ilya Naymushin/Reuters)

A dog jumps into the air to catch a ball along the beach near the County Kerry village of Rossbeigh, Ireland, February 4, 2018. (Photo by Clodagh Kilcoyne/Reuters)

European bisons (also known as Wisent) at the Bison farm in Muczne, southeastern Poland, 30 December 2018. The Bison farm is a continuation of bison breeding in Bieszczady, which was started in 1963. Here visitors can admire the bison of Bialowieza-Caucasian line, also called the mountain race. The European Bison is the national animal of Poland. (Photo by Darek Delmanowicz/EPA/EFE)

A street entertainer waits for tourists in Havana, Cuba on October 2009. (Photo by Desmond Boylan/Reuters)

A man looks at a car hit by a post after a tornado ripped through a neighbourhood in Havana, Cuba on January 28, 2019. (Photo by Fernando Medina/Reuters)