In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

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)

Enthusiasts gathered at Cad East in Snowdonia National Park, England to take pictures of F-15 Eagle fighters as they completed the Mach Loop, November 2017. (Photo by Caters News Agency)

Children enjoy a sledge ride past ice swimming fans at the Zalew Zegrzynski lake in Nieporet, Poland, Sunday, February 25, 2018. A cold wave hit Poland with the temperature minus 8 degree Celsius (17.6 Fahrenheit) during the day and dropping to minus 16 degree Celsius (3.2 Fahrenheit) in the night in central Poland. (Photo by Alik Keplicz/AP Photo)

Fans dressed up in costume await the cast members on the red carpet at the world premiere of the film "The Avengers: Endgame" in Los Angeles, California, April 22, 2019. (Photo by Mario Anzuoni/Reuters)

Life in lockdown: Schoolteacher Marzio Toniolo, 35, takes a picture of his two-year-old daughter Bianca painting his toenails as they while away time at home in San Fiorano, one of the original “red zone” towns in northern Italy that has now been extended to the whole country, as his wife, Bianca's mum Chiara Zuddas looks out from their balcony, March 20, 2020. Toniolo has been documenting how his family has dealt with being under quarantine since it began for them in February. (Photo by Marzio Toniolo via Reuters)

A Polish girl and a boy throw water over each other on Wet Monday in Szczecin, northwestern Poland, 13 April 2020. Wet Monday is a Catholic celebration held on Easter Monday mostly in Poland, but also in the Czech Republic, Slovakia, Hungary and some parts of western Ukraine. Due to the lockdown it is forbidden to celebrate this holiday in public. (Photo by Marcin Bielecki/EPA/EFE)

A medical worker in protective gear sprays mist on her colleague during a hot day at an outdoor clinic for coronavirus tests at a public health facility in the southwestern city of Gwangju, South Korea, 05 June 2020. (Photo by Yonhap/EPA/EFE)