University students wearing Guy Fawkes masks pose for a photoshoot of a graduation ceremony to support anti-government protests at the Hong Kong Polytechnic University, in Hong Kong, China on October 30, 2019. (Photo by Tyrone Siu/Reuters)

A woman tries to cross a flooded street as people walk on a trestle bridge during high water, in Venice, northern Italy, Friday, November 15, 2019. Exceptionally high tidal waters returned to Venice on Friday, prompting the mayor to close the iconic St. Mark’s Square and call for donations to repair the Italian lagoon city just three days after it experienced its worst flooding in 50 years. (Photo by Andrea Merola/ANSA via AP Photo)

North Korean bodyguards run along a limousine transporting Kim Jong Un upon his arrival in Dong Dang, Vietnam, February 26, 2019. The second meeting of the US President and the North Korean leader, running from 27 to 28 February 2019, focuses on furthering steps towards achieving peace and complete denuclearization of the Korean peninsula. (Photo by Reuters/Stringer)

Children wave Vietnamese and American flags while waiting for arrival of U.S. President Barack Obama (not pictured) before a welcoming ceremony at the Presidential Palace in Hanoi, Vietnam May 23, 2016. (Photo by Reuters/Kham)

Workers reinforce the electric pylons at a flooded area as Typhoon Nepartak approaches in Xuancheng, Anhui Province, China, July 9, 2016. (Photo by Reuters/Stringer)

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

A pupil of the Dao ethnic tribe returns home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

A pink elephant balloon, one of the entries in the Canadian Hot Air Balloon Championships, lands in a field in High River September 27, 2013. The event is a qualifier for the World Hot Air Balloon Championships in Sao Paulo in 2014. (Photo by Mike Sturk/Reuters)