A Chesterfield Borough Police telephone operator tests a gasmask with built in earpiece and microphone. The telephone service is considered one of the most important links in the coordination of ARP operations and must remain operational during air raids, 12th April 1939. (Photo by Fox Photos/Hulton Archive/Getty Images)

A devotee, dressed as Hindu God Shiva, looks out from a window as he waits to perform during the annual Shiva Gajan religious festival on the outskirts of Agartala, India April 13, 2018. (Photo by Jayanta Dey/Reuters)

Visitors take photos of a child dressed in a traditional costume before a folk performance in Panyu, Guangdong province, China on April 20, 2018. (Photo by Reuters/China Daily)

An attendee takes a selfie at KCON USA, billed as the world's largest Korean culture convention and music festival, in Los Angeles, California on August 11, 2018. K-pop acts sing or rap in Korean, often with snippets of English. On the Web, where K-pop fandom thrives, many music videos include subtitles. (Photo by Mike Blake/Reuters)

A USGS geologist making observations of the fissure 8 lava channel at sunset is pictured in this July 3, 2018 fisheye lens handout photograph near the Kilauea volcano eruption in Hawaii, U.S. (Photo by USGS/Handout via Reuters)

An Indian Sikh devotee spits fire as he performs during religious procession ahead of the birth anniversary of the first Sikh Guru or master, Sri Guru Nanak Dev Ji, the founder of Sikhism, in Jammu, the winter capital of Kashmir, India, 21 November 2018. The birth anniversary of Guru Nanak Dev Ji will be observed on 23 November 2018. (Photo by Jaipal Singh/EPA/EFE)

A woman reacts after identifying a relative among the bodies of tsunami victims in Carita, Indonesia, Sunday, December 23, 2018. The tsunami occurred after the eruption of a volcano around Indonesia's Sunda Strait during a busy holiday weekend, sending water crashing ashore and sweeping away hotels, hundreds of houses and people attending a beach concert. (Photo by Fauzy Chaniago/AP Photo)

Tourists enjoy hot pot and spring at the hotpot shaped spring during winter at a hotel in Hangzhou, east China's Zhejiang Province on December 26, 2018. (Photo by Sipa Asia/Rex Features/Shutterstock)