A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

A Hindu holy man, or sadhu, smokes marijuana in a chillum at the premises of Pashupatinath Temple, ahead of the Shivaratri festival in Kathmandu, Nepal February 15, 2017. (Photo by Navesh Chitrakar/Reuters)

A workman sweeping the highest sidewalk in the world, the 81st story of the Empire State Building, the world's tallest building, to the top of which the greatest dirigible “Los Angeles” will attempt to moor, New York, New York, early 1930s. This photo was made 1,248 feet above street level. (Photo by Adam Glickman/Underwood Archives/Getty Images)

Pride rally 2017 on fifth avenue in Manhattan, New York, June 25, 2017. Thouands cheered as members of LGBT community danced and marched under a bright summer sun. Many participants carried political themed signs as President Trump's adminstration has angered some in the LGBT community. (Photo by R. Umar Abbasi)

Dancers perform during the Sambodromo do Brasil jungle party in the Cave stage, Elrow Town at Queen Elizabeth Olympic Park on August 18, 2018 in London, England. (Photo by Ollie Millington/Redferns)

Festivalgoers dance during the Balaton Sound music festival in Zamardi, Hungary, July 5, 2018. Balaton Sound is one of Europe's largest open air electronic music festivals. Held annually since 2007 on the southern bank of Lake Balaton, Hungary, it features live acts and DJ's from all around the world, from established artists to new names. The event was co-created by the organizers of Sziget Festival. (Photo by Bernadett Szabo/Reuters)

Iranian skiers rest at the Dizin ski resort, northwest of Tehran January 15, 2016. (Photo by Raheb Homavandi/Reuters/TIMA)

Damselflies covered in dew rest on a wild flower by the Po River, northern Italy on August 15, 2016. (Photo by Alberto Ghizzi Panizza/Barcroft Images)