The Canary Wharf financial district stands in London, Britain on August 11, 2019. (Photo by Simon Dawson/Reuters)

Students from Langata primary school run past riot police as they protest against a perimeter wall illegally erected by a private developer around their school playground in Kenya's capital Nairobi January 19, 2015. Riot police used teargas to disperse students at a school in Nairobi as the children protested against the potential loss of their playground. The playground was fenced off in December, during the school holidays, by a prominent developer who also claims ownership of the land. The title to the contested site is said to be in the name of Airport View Housing Limited, according to local media, with plans to use the space to build a parking lot for a hotel. (Photo by Thomas Mukoya/Reuters)

This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

A Carlsbad,Calif. police officer turns traffic away as flames leap behind him Wednesday, May 14, 2014, in Carlsbad, Calif. Weather conditions that at least temporarily calmed allowed firefighters to gain ground early Wednesday on a pair of wildfires that forced thousands of residents to leave their homes. (Photo by AP Photo)

Protester Lauren Digioia wears police tape during an Occupy Wall Street protest in Union Square on March 19, 2012 in New York City. Protesters affiliated with the movement are gathering in Union Square today following 73 arrests at a six-month anniversary rally at Zuccotti Park over the weekend. (Photo by Mario Tama/Getty Images)

A woman walk by South Korean police during a anti-terror exercise on March 9, 2012 in Seoul, South Korea. The drill is part of South Korea's preparation for the upcoming 2012 Seoul Nuclear Security Summit, scheduled for March 26 and 27. Some 50 world leaders, including U.S. President Barack Obama, are expected to attend the summit to discuss how to make the world safe without nuclear weapons. (Photo by Chung Sung-Jun/Getty Images)

A girl walks past campaign posters for long-time President Yoweri Museveni, as well as for local members of Parliament, on a street in Kampala, Uganda Wednesday, February 17, 2016. On the eve of presidential elections, a heavy police and military presence could be seen in the capital Kampala. (Photo by Ben Curtis/AP Photo)

Indian police detain a Tibetan activist during a protest held to mark the 57th anniversary of the Tibetan uprising against Chinese rule, outside the Chinese embassy in New Delhi, India, March 10, 2016. (Photo by Cathal McNaughton/Reuters)