Revelers dance at the Old Settler's Music Festival in Driftwood, Texas, U.S. on April 22, 2017. (Photo by Mohammad Khursheed/Reuters)

Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

Festival goers participate in a dance class on embracing kinetic intimacy in the dance shala a the Oregon Eclipse Festival, August 20, 2017, at Big Summit Prairie ranch in Oregon' s Ochoco National Forest near the city of Mitchell ahead of the total solar eclipse on August 21, 2017. (Photo by Robyn Beck/AFP Photo)

General Maurice Gamelin, General Officer commanding the French Armies, is on a four day visit to England. He went to the staff college at Minley and is seen inspecting an anti-tank gun at Aldershot, on June 7, 1939. (Photo by AP Photo)

On the second straight day of record-setting temperatures, Maddy Hacker is hoisted up by friend Jasmine Harper, both of McLean, Virgnia, as they attempt an acrobatic stunt in front of the U.S. Capitol in Washington, U.S., February 21, 2018. (Photo by Kevin Lamarque/Reuters)

Indian artists dress up as the Hindu deity “Hanuman” – the monkey God in Hindu mythology – to mark the Rama Navami festival in Bangalore on March 25, 2018. Rama Navami is a spring Hindu festival that celebrates the birthday of the deity Rama. He is particularly important to the Vaishnavism tradition of Hinduism, as the seventh avatar of Vishnu. (Photo by Manjunath Kiran/AFP Photo)

Residents watch volcanic smoking and ashes rising from Mount Sinabung during an eruption in Karo, North Sumatra, Indonesia, February 24, 2016. Authorities have repeatedly called on local residents to remain patient in dealing with the impact of Sinabung's eruptions, which some experts have predicted will continue for five more years. (Photo by Xinhua/Barcroft Media)

An overcrowded dinghy with migrants from different African countries is followed by members of the German NGO Jugend Rettet as they approach the Iuventa vessel during a rescue operation, off the Libyan coast in the Mediterranean Sea September 21, 2016. (Photo by Zohra Bensemra/Reuters)