Robot pianist Teo Tronico performs at the World Robot Conference (WRC) 2017 at Etrong International Exhibition & Convention Center on August 22, 2017 in Beijing, China. The World Robot Conference 2017 is held from August 23 to 27 in Beijing. (Photo by Liu Guanguan/China News Service/VCG via Getty Images)

Indian Air Force personnel parade during the 85th Air Force Day celebrations at Hindon Air Force base in Ghaziabad on October 8, 2017. (Photo by AFP Photo/Stringer)

A Hong Kong Correctional Services Dog Unit (CSDU) officer demonstrates training at the CSDU training facility in Stanley, Hong Kong, China, 27 February 2018. The Hong Kong CSDU consists of 29 staff members divided across six dog teams. According to the department's latest figure from 2017, the average daily penal population of Hong Kong was 8,529. (Photo by Jérôme Favre/EPA/EFE)

A man exercises in the early morning on a hilltop overlooking Kabul, Afghanistan March 3, 2016. (Photo by Mohammad Ismail/Reuters)

This picture taken on January 3, 2019 shows a Vietnamese woman collecting incense sticks in a courtyard in the village of Quang Phu Cau on the outskirts of Hanoi. In Vietnam's “incense village”, hundreds of workers are hard at work dying, drying and whittling down bamboo bark to make the fragrant sticks ahead of the busy lunar new year holiday. (Photo by Manan Vatsyayana/AFP Photo)

Festival goers enjoy Parklife festival at Heaton Park on June 09, 2019 in Manchester, England. The risky outfits are back on day two, but at least everyone's not covered in mud this time as the sun shines over Manchester. (Photo by BackGrid)

A Ballet dancer prepares backstage during the final dress rehearsal for the famous Nutcracker ballet by Pyotr Tchaikovsky at the Joburg Ballet, Johannesburg, South Africa, 04 October 2018. The premiere of Nutcracker is scheduled for 05 October and the show will run for two weeks. (Photo by Kim Ludbrook/EPA/EFE)

Dancers resting on the rooftop of the SKD Theatre Asakusa, Tokyo, 1949. (Photo by Tanuma Takeyoshi/The Guardian)