Planes for Team Oracle perform over downtown San Francisco during a practice session for San Francisco Fleet Week October 5, 2007 in San Francisco, California. (Photo by Jed Jacobsohn/Getty Images)

Sebastien Bourdais, of Colombia, makes a corner during practice for the IndyCar auto race Saturday, June 13, 2015, in Toronto. (Nathan Denette/The Canadian Press via AP)

Indonesian soldiers take part in a handling riots practice ahead of the elections at their military home base in Banda Aceh, Aceh province on April 9, 2019. (Photo by Chaideer Mahyuddin/AFP Photo)

In this photo taken Friday, December 9, 2016, young ballerinas practice under the instruction of Kenyan ballet dancer Joel Kioko, 16, in a room at a school in the Kibera slum of Nairobi, Kenya. (Photo by Ben Curtis/AP Photo)

A man holds up for a picture a one hundred trillion Zimbabwean dollars note inside a shop in Harare, Zimbawe, June 12, 2015. Hyperinflation in Zimbabwe was a period of currency instability that began in the late 1990s shortly after the confiscation of private farms from landowners, towards the end of Zimbabwean involvement in the Second Congo War. During the height of inflation from 2008 to 2009, it was difficult to measure Zimbabwe's hyperinflation because the government of Zimbabwe stopped filing official inflation statistics. However, Zimbabwe's peak month of inflation is estimated at 79.6 billion percent in mid-November 2008. (Photo by Philimon Bulawayo/Reuters)

In this Sunday June 13, 1988 file photo West German police officers arrest an English soccer hooligan who sticks out his tongue. Rioting broke out between some 100 hooligans and the police in downtown Stuttgart, West Germany following the European Soccer Championships match between England and Ireland. England was defeated by Ireland 0-1. (Photo by Kraufmann/AP Photo/File)

Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)