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)
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)
A military band conductor practices during rehearsal ahead of the opening session of Chinese People's Political Consultative Conference (CPPCC) at the Great Hall of the People in Beijing, March 3, 2015. REUTERS/Jason Lee
Young girls practice acrobatic skills in the Sichuan Provincial Art School July 14, 2008 in Chengdu of Sichuan Province, China. (Photo by China Photos/Getty Images)
Young gymnasts practice pull-up on a bar at a gymnasium of a sports school in Jiaxing, Zhejiang province April 11, 2015. (Photo by William Hong/Reuters)
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)
Waves crash against the lighthouse at Newhaven, England, Monday March 28, 2016. Some flights at London's Gatwick and Heathrow airports have been diverted due to high winds battering much of Britain and western France. The high winds from a storm caused 87 cancellations and 43 diversions at Gatwick and Heathrow because flights had trouble landing safely. (Photo by Steve Parsons/PA Wire via AP Photo)