In this aerial photo taken on March 28, 2019 a hot air balloon flies over Putrajaya during the international hot air balloon festival in Putrajaya, Malaysia. (Photo by Mohd Rasfan/AFP Photo)

Two men push a classic Messerschmidt KR200 “Kabinenroller” at the 7th Cairo Classic Meet in Cairo, Egypt, 23 March 2019. The exhibition for classic cars is held at the Smart Village in Cairo. The exhibition is held to exchange experiences in how to preserve the old cars, and also for promoting tourism. (Photo by Mohamed Hossam/EPA/EFE)

Mil Mi-8 combat helicopter flies over Moscow, Russia on May 7, 2019 during the dress rehearsal of a Victory Day air show marking the 74th anniversary of the victory over Nazi Germany in the 1941-1945 Great Patriotic War, the Eastern Front of World War II. (Photo by Sergei Savostyanov/TASS)

A family take a souvenir picture next to giant male panda Xiao Liwu, who was born at the San Diego Zoo and will be repatriated to China with his mother Bai Yun, bringing an end to a 23-year-long panda research program in San Diego, California, U.S., April 18, 2019. (Photo by Mike Blake/Reuters)

In this photo taken on Sunday, March 10, 2019, a little girl laughs during a ritual marking the upcoming Clean Monday, the beginning of the Great Lent, 40 days ahead of Orthodox Easter, on the hills surrounding the village of Poplaca, in central Romania's Transylvania region. Romanian villagers burn piles of used tires then spin them in the Transylvanian hills in a ritual they believe will ward off evil spirits as they begin a period of 40 days of abstention, when Orthodox Christians cut out meat, fish, eggs, and dairy. (Photo by Vadim Ghirda/AP Photo)

View of the Villarrica volcano taken from Pucon, some 800 kilometres south of Santiago, showing signs of activity on December 06, 2017. (Photo by Christian Miranda/AFP Photo)

A man looks at a photograph by French photographer Robert Doisneau entitled “The Fate Line: Pablo Picasso at Vallauris, 1952” during the presentation of the photo-exhibition “Picasso, photographer's gaze”, on June 5, 2019 at the Picasso Museum in Barcelona. (Photo by Lluis Gene/AFP Photo)

Sinabung mountain spews volcanic smoke in Tiga Pancur Village, Karo, North Sumatra, Indonesia, 09 June 2019. According to BNPB, Mount Sinabung erupted, blowing volcanic ash more than 7,000 meters high. Sinabung is one of the most active volcanos in Indonesia. It erupted in 2010 and since then killed 17 people in eruptions in 2014 and another nine people in 2016. (Photo by Sarianto Sembiring/EPA/EFE)