Daniel Cheong, a dog behaviorist and trainer, steps over a leash as he walks a pack of dogs in Arlington, Va. on November 13, 2018. (Photo by Ricky Carioti/The Washington Post)

A leopard attacks an Indian man as others climb a wall to get away from the animal in Lamba Pind area in Jalandhar on January 31, 2019. After a leopard was spotted in a house in Lamba Pind area of Jalandhar city, subsequent attempts to capture it led to the animal attacking at least six people, though none was injured seriously, local media said. (Photo by Shammi Mehra/AFP Photo)

In collaboration with the Pennsylvania Department of Transportation, Allegheny College art students repurpose used street signs as art materials to create the PennDOT Road Sign Sculpture Garden in Meadville, Pennsylvania, USA on August 19, 2017. (Photo by Brian Cahn/ZUMA Wire/Rex Features/Shutterstock)

In this September 21, 2017, local villagers repair a fishing boat in Shah Porir Dwip, an island by the Bay of Bengal at Bangladesh’s southern tip. This island can mean both hope and death for the Rohingya Muslims who are desperate to escape the violence that has engulfed their lives in Myanmar’s Rakhine state. High tide or low, day or night, rough waters or calm, when they can find a boat, the Rohingya take their chance to flee to Bangladesh. More than 430,000 have left Myanmar in less than a month. (Photo by Bernat Armangue/AP Photo)

Armed female members of the militant Palestinian group Islamic Jihad carry Kalashnikov assault rifles as they take part in a rally to protest against US President Donald Trump's decision to recognise Jerusalem as the capital of Israel, in Gaza City on December 11, 2017. (Photo by Mohammed Abed/AFP Photo)

Young children at a Bristol, Great Britain health centre unsure of the benefits of sun-lamps and the special glasses that must be worn, July 1948. The health centre was part of the newly introduced free National Health Service. (Photo by Popperfoto/Getty Images)

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)

A herd of elephants cross a road that passes through the flooded Kaziranga National Park in the northeastern state of Assam, India, July 12, 2017. (Photo by Anuwar Hazarika/Reuters)