Polar bear twins make their first public appearance with their mother “Freedom” at Ouwehands Zoo Rhenen, in Rhenen, The Netherlands, 19 February 2015. The twins, who were born in November 2014, have not been named because their gender has not yet been determined. (Photo by Bart Maat/EPA)

Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

A model falls over on the runway in a design by Victoria Bliss during the Project NextGen show at Mercedes-Benz Fashion Week Resort 18 Collections at Carriageworks on May 16, 2017 in Sydney, Australia. (Photo by Stefan Gosatti/Getty Images)

A picturesque supercell formation in the northwest of Booker, Texas from June 2013. (Photo by Mike Olbinski/Barcroft Media)

A man is silhouetted as he stands on a walkway in the sky lobby at the Chancellery, the seat of German Chancellor Angela Merkel (not pictured) in Berlin, May 7, 2014. (Photo by Thomas Peter/Reuters)

An Afghan policeman stands guard as smoke and flames rise from the site of a huge blast struck near the entrance of Kabul's international airport, in Kabul on August 10, 2015. A huge blast struck near the entrance of Kabul's international airport on August 10 during the peak lunchtime period, officials said, warning that heavy casualties were expected. “The explosion occurred at the first check point of Kabul airport”, said deputy Kabul police chief Sayed Gul Agha Rouhani. (Photo by Shah Marai/AFP Photo)

A goat begs for food as people have a meal and beer at the Beichelstein-Alpe outdoor restaurant near Seeg, southern Germany, on March 27, 2017. (Photo by Karl-Josef Hildenbrand/AFP Photo/DPA)

In this Saturday, February 16, 2019 photo, carnival revelers dressed as characters from the movie “La Casa de Papel” pose for a picture during the “Desliga da Justica” block party in Rio de Janeiro, Brazil. “Desliga” means in Portuguese to turn something off, and this street party is a parody of the Justice League. (Photo by Leo Correa/AP Photo)