In this aerial view Haitian migrants queue to receive food at a shelter in Ciudad Acuna, Coahuila State, Mexico, on September 23, 2021. At least 50 police vehicles carrying more than a hundred agents are blocking the border crossing at the river that separates the Mexican city of Ciudad Acuña from the United States, AFP reported. (Photo by Pedro Pardo/AFP Photo)

Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

A female Chinese People's Liberation Army soldier looks at members of an honor guard preparing for a welcome ceremony for visiting German President Joachim Gauck, outside the Great Hall of the People in Beijing, Monday, March 21, 2016. (Photo by Andy Wong/AP Photo)

A picture taken with a drones shows Kayakers make use of the current that flows over a dike in the flood plains of the Waal river, with the Waal bridge of Nijmegen in the background in Lent, the Netherlands, 04 February 2021. The heavy rainfall and snow melt in southern Germany has caused a significant rise in the water level in various places in the Netherlands. (Photo by Robin Van Lonkhuijsen/EPA/EFE)

Graffiti is painted on the bathroom walls at a restaurant in the Williamsburg area of Brooklyn borough in New York, United States, October 1, 2015. Some 2.4 billion people around the world don't have access to decent sanitation and more than a billion are forced to defecate in the open, risking disease and other dangers, according to the United Nations. To mark World Toilet Day on November 19, Reuters photographers captured pictures of toilets in cities, towns and villages around the globe. (Photo by Shannon Stapleton/Reuters)

The Mausoleum of the Giants, an immersive solo show of monumental sculptures by the artist Phlegm, is installed at Taylor’s Eye Witness Works in Sheffield, England on March 14, 2019. (Photo by Danny Lawson/PA Wire Press Association)

The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/Reuters)