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)

In this Friday, February 6, 2015 photo, sandhill cranes begin to stir after resting for the night at a roosting location along their winter migration route in Cecilia, Ky. According to counts made by biologists with the Kentucky Fish and Wildlife Resources, about 12,000 of the birds have stopped in Cecilia this week during their winter northward migration on their way to their nesting grounds in the Great Lakes region. (Photo by David Stephenson/AP Photo)

Meanwhile, over on Portobello beach, members of the Upsala circus take a stroll before their fringe debut, Ping-Pong Ball Effect in Edinburgh, England on August 1, 2017. (Photo by Murdo Macleod/The Guardian)

Revellers attend the 25th edition of the Sziget Festival on August 9, 2017 in Budapest, Hungary. The Sziget Festival, one of the largest music and cultural festivals in Europe, celebrates its 25th anniversary in 2017, taking place from August 9-16 on the Hajogyari Sziget in Budapest. (Photo by Laszlo Mudra/Rockstar Photographers)

In this Wednesday, April 12, 2017, photo, waitresses wait outside a restaurant in Pyongyang, North Korea. A generational divide is quietly growing in North Korea, often hidden behind relentless propaganda. On the streets there are young women in not-quite mini-skirts and teenage boys with baseball hats cocked sideways, K-pop style. (Photo by Wong Maye-E/AP Photo)

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)

A man looks at kebabs cooking on the street side in Rawalpindi, Pakistan October 2, 2017. (Photo by Caren Firouz/Reuters)