Opposition students march against Venezuelan President Nicolas Maduro's government in Caracas February 12, 2015. Venezuelan troops blocked students during marches against Maduro on Thursday as pro-government supporters also rallied on the anniversary of 2014 protests that led to 43 deaths. In Caracas, troops cordoned off scores of students on an unauthorized march to a church where they planned a mass in honour of demonstrators who died. (Photo by Jorge Silva/Reuters)

Kenyan riot police officers raise batons over a man during a demonstration of Kenya's opposition supporters in Nairobi, on May 16, 2016. Opposition protestors led by former Prime Minister Raila Odinga gathered outside the Indepedent Electoral and Boundaries Comission building to demand the dismissal of IEBC commissioners, after alleged bias towards the ruling Jubillee Alliance Party. (Photo by Carl De Souza/AFP Photo)

Tribesmen loyal to the Houthi movement perform the Baraa dance during a gathering to show support to the movement in Sanaa, Yemen, May 19, 2016. Bara or Baraa dance is one of the several traditional outdoor dances performed by men in the country of Yemen. Bara dance literally means a dagger dance, where each dancer holds a dagger. The style of the Bara dance differs from tribe to tribe. It is performed on special occasions. (Photo by Khaled Abdullah/Reuters)

Supporters of the PHTK presidential candidate Jovenel Moise strike zombie poses during a protest march demanding the resignation of interim President Jocelerme Privert in Port-au-Prince, Haiti, Tuesday, June 7, 2016. The electoral council of Haiti has decided to re-do a presidential election that a special commission determined was marred by fraud. (Photo by Dieu Nalio Chery/AP Photo)

A handout phptopgraph made avaiable by NASA showing Russian support personnel roll the Soyuz TMA-19M spacecraft after it landed with with with Expedition 47 crew members Tim Kopra of NASA, Tim Peake of the European Space Agency, and Yuri Malenchenko of Roscosmos near the town of Zhezkazgan, Kazakhstan 18 June 2016. Kopra, Peake, and Malenchenko are returning after six months in space where they served as members of the Expedition 46 and 47 crews onboard the International Space Station. (Photo by Bill Ingalls/EPA/NASA)

A woman walks past the barbed wire separating Belarusian servicemen and Belarusian opposition supporters during a rally in Minsk, Belarus, Sunday, August 30, 2020. Tens of thousands of demonstrators have gathered in the capital of Belarus, beginning the fourth week of daily protests demanding that the country's authoritarian president resign. The protests began after an Aug. 9 presidential election that protesters say was rigged and officials say gave President Alexander Lukashenko a sixth term in office. (Photo by Tut.By via AP Photo)

Belarusian police officers detain an opposition supporter during a rally to protest against the disputed August 9 presidential elections results in Minsk on September 6, 2020. Tens of thousands of Belarusians staged a peaceful new march on September 6, keeping the pressure on strongman Alexander Lukashenko who has refused to quit after his disputed re-election and turned to Russia for help to stay in power. (Photo by TUT.BY/AFP Photo)

Ellen MacRae a student from Edinburgh University take a lateral flow antigen test at a test centre which is also open to students in Edinburgh Napier University, Queen Margaret University and SRUC on December 1, 2020 in Edinburgh, Scotland. The programme is running in partnership between the University of Edinburgh and other Scottish universities, the Scottish Government and NHS Test and Protect, supporting students leaving their term-time accommodation to travel home at the end of term for the winter break. (Photo by Jeff J. Mitchell/Getty Images)