A ballet dancer stretches backstage during Nacho Duato's “The Nutcracker” at the Mikhailovsky Theatre in St. Petersburg, Russia November 21, 2015. For theatregoers in St Petersburg, Nacho Duato's “The Nutcracker” demonstrates the global appeal of a Christmas classic. When the curtain rises at the Mikhailovsky Theatre, among the oldest opera and ballet houses in Russia, it's the culmination of hundreds of hours of toil and sweat by dancers, costume makers, set designers and musicians playing the famous score by Pyotr Tchaikovsky. (Photo by Grigory Dukor/Reuters)

American film and theater actress, singer and dancer Shirley MacLaine. (Photo by Philippe Halsman)

Margaret Morris dancers exercising on the sands at Saint-Idesbald. (Photo by Fox Photos/Getty Images). August 1929

Two traditional folk dancers performing in Teheran, Iran. (Photo by Keystone Features/Getty Images). 25th January 1961

A dancer performs as visitors take pictures at an auto show in Tianjin, China April 28, 2016. (Photo by Reuters/Stringer)

Dancers perform during La Paz Fashion Week in La Paz, Bolivia, February 7, 2019. (Photo by David Mercado/Reuters)

A dancer attends the final rehearsal for the new “VIVID Grand Show” at Friedrichstadt-Palast in Berlin, Germany, September 26, 2018. (Photo by Hannibal Hanschke/Reuters)

Dancers of the English National Ballet perform “Strictly Gershwin” at the Coliseum on January 10, 2012 in London, England. (Photo by Ian Gavan/Getty Images)