South Vietnamese forces escort suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street February 1, 1968, early in the Tet Offensive. Moments later, Lem was executed by Gen. Nguyen Ngoc Loan, chief of the national police. (Photo by Eddie Adams/AP Photo)

A man rides a bike on a submerged road alongside a boat at Demra area in Dhaka on July 24, 2020. As many as 20 districts including the latest additions Chandpur, Brahmanbaria, and Naogaon have so far been hit with the worsening flood situation across Bangladesh and many more areas might be inundated if the situation does not improve soon, said Flood Forecasting and Warning Centre (FFWC). (Photo by Sultan Mahmud Mukut/SOPA Images/LightRocket via Getty Images)

A worker wearing a protective face mask, cleans up the road in front of a mural in Jakarta, Indonesia, 24 July 2020. Indonesian government has assigned a new team to rebuild the national economy amid the coronavirus pandemic. The country has started to ease COVID-19 lock-down restrictions in an effort to restart the economies and help people in their daily routines after the outbreak of coronavirus pandemic. (Photo by Mast Irham/EPA/EFE)

Enthusiasts participate in the historical re-enactment of the Sevastopol Fortress assault, which took place during the Crimean War of 1853-1856, at a military historical festival in Sevastopol, Crimea, September 5, 2020. (Photo by Alexey Pavlishak/Reuters)

An indigenous woman participates in a parade called "International Indigenous Beauty" during the first World Games for Indigenous Peoples in Palmas, Brazil, October 24, 2015. Billed as the indigenous Olympics, the games are expected to attract nearly 2,000 athletes from dozens of Brazilian ethnicities, as well as from such far-flung nations as Ethiopia and New Zealand. (Photo by Ueslei Marcelino/Reuters)

A woman poses for pictures with skulls made of cardboard placed on an altar next to the San Francisco church in Mexico City during the celebration of All Souls Day on November 2, 2015. (Photo by Yuri Cortez/AFP Photo)

A girl runs from waves crashing over the promenade on December 24, 2015 in Blackpool, England. The Met Office is warning of 80mph winds and torrential downpours over the Christmas holidays, as dozens of flood alerts are issued for already devastated regions. (Photo by Nigel Roddis/Getty Images)

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)