A police officer detains a woman on suspicion of collaborating with the 18th street gang during a "Safe House" operation at the Concepcion neighbourhood in San Salvador, July 2, 2015. Salvadoran police make “Safe House” operations at dangerous neighbourhoods of the capital to prevent murders, according to local media. (Photo by Jose Cabezas/Reuters)

This image made available by the Johns Hopkins University Applied Physics Laboratory on Wednesday, May 31, 2017 depicts NASA's Solar Probe Plus spacecraft approaching the sun. On Wednesday, NASA announced it will launch the probe in summer 2018 to explore the solar atmosphere. It will be subjected to brutal heat and radiation like no other man-made structure before. (Photo by Johns Hopkins University Applied Physics Laboratory via AP Photo)

“Be prepared” is the motto of petite Doris Sherrell, vocalist and dancer with “Blackouts of 1942”. In the event of a bombing, the young lady had her social security number tattooed on one leg by artist Jack Julian, and address placed on the other limb for means of identification in Los Angeles, September 29, 1942. (Photo by AP Photo)

California “weed nun” Christine Meeusen, 57, (R), and India Delgado, who goes by the name Sister Eevee, smoke a joint at Sisters of the Valley near Merced, California, April 18, 2017. (Photo by Lucy Nicholson/Reuters)

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)

A demonstrator catches fire during clashes with riot police within a protest against Venezuelan President Nicolas Maduro, in Caracas on May 3, 2017. Venezuela's angry opposition rallied Wednesday vowing huge street protests against President Nicolas Maduro's plan to rewrite the constitution and accusing him of dodging elections to cling to power despite deadly unrest. (Photo by Ronaldo Schemidt/AFP Photo)

Catherine Hollis of Chester, Pa., and Izzy Weintraub of Atlantic City eat Cherrystone clams at Atlantic City's annual clam-eating contest September 16, 1946. They finished 96 and 66 clams respectively in 20 minutes. (Photo by Sam Myers/AP Photo)

Comedian Chevy Chase gets a kiss on his ear from co-star Benji as the two held a press conference in Los Angeles, September 6, 1979, at which they announced their up-coming movie “Oh Heavenly Dog” would begin filming this month. The film will be shot on location in London, Berlin and Paris; but due to British quarantine laws a double will be used for Benji at the London location. (Photo by Nick Ut/AP Photo)