Ethnic Miao women wearing traditional costumes take part in a parade during the traditional Lusheng (reed-pipe wind instrument) festival in Gulong, Guizhou province, China November 15, 2017. (Photo by Reuters/China Stringer Network)

Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

Two and a half year-old Jennifer Martin in tears during a visit to Santa at Harrods department store in London, 10th December 1949. (Photo by William Vanderson/Fox Photos/Hulton Archive/Getty Images)

An Army Sikorsky R-5 helicopter, undergoing record trials, demonstrates its lifting power by carrying 17 persons and pilot aloft as female onlookers wave in Bridgeport, Conn., January 10, 1946. During the tests records were claimed for altitude speed and both altitude and speed with payload. (Photo by Anthony Camerano/AP Photo)

Police detain an alleged thief in Lagos' Tafawa Balewa Square where the official People's Democratic Party (PDP) opposition party is holding a rally on February 12, 2019. Nigerians will cast their ballots on February 16 in presidential and legislative elections. The presidential contest will see incumbent Muhammadu Buhari seek to win a second four-year term against former vice president Atiku Abubakar in what is expected to be a close race. (Photo by Luis Tato/AFP Photo)

A guest dressed as a zombie attends the Middle East Film & Comic Con (MEFCC) in Gulf emirate of Dubai, United Arab Emirates, 11 April 2019. The event runs until 13 April 2019. (Photo by Ali Haider/EPA/EFE)

A junk boat sails in to dock as a woman sits on the pier in the central district of Hong Kong on May 15, 2019. (Photo by Isaac Lawrence/AFP Photo)

People wear clothing to protect them from the heat while riding along a street in Hanoi, Vietnam, 24 April 2019. North and central Vietnam was recently affected by extreme hot weather, with the highest temperatures reaching over 40 degrees Celcius, according to the National Centre for Hydro-meteorological Forecasting. (Photo by Luong Thai Linh/EPA/EFE)