Photographer Andy Hall joins the thousands of fans from west Africa who have gathered for Baaba Maal's annual Blues du Fleuve festival in Senegal. Here: Dancers wait to perform on stage. (Photo by Andy Hall/The Observer)

People take part in the Classic Ride Rally in downtown Valencia, eastern Spain, 23 November 2014. Some hundred people on classic bikes from the 20's to the 70's participated in the rally. (Photo by Kai Foersterling/EPA)

In this December 18, 2013 photo released by Six Flags Discovery Kingdom, 32 men dressed as Santa Claus ride the 150-foot tall SkyScreamer tower swing ride at Six Flags Discovery Kingdom in Vallejo, Calif. (Photo by Jason Quintos/AP Photo/Six Flags Discovery Kingdom)

Nicki Minaj attends the 14th Annual CFDA Vogue Fashion Fund Gala at Weylin on Monday, November 6, 2017, in New York. (Photo by Splash News and Pictures)

Sanne Vloet, Sui He, Lais Ribeiro, Taylor Hill, Romee Strijd and Megan Williams pose backstage during 2017 Victoria's Secret Fashion Show In Shanghai at Mercedes-Benz Arena on November 20, 2017 in Shanghai, China. (Photo by Kevin Mazur/Getty Images for Victoria's Secret)

Danielle Sellers attends The Beauty Awards at Tower of London on November 28, 2017 in London, England. (Photo by Lia Toby/WENN)

Dayane Mello attends the photocall for the television miniseries “The Young Pope” at the 73rd Venice Film Festival in Venice, Italy, September 3, 2016. (Photo by Alessandro Bianchi/Reuters)

Two young women, having enjoyed a drink at a party, dance together in Tehran, Iran. Although unrelated men and women are forbidden to socialise together many people ignore these strictures in the privacy of their own homes. (Photo by Hossein Fatemi/Reuters/Panos Pictures/Courtesy of World Press Photo Foundation)