In this photo taken on July 19, 2014, a man looks at an excavation as an A.R.M.H., Association for the Recovery of Historical Memory, volunteer digs on the search for the body of Perfecto de Dios, in a hidden grave in Chaherrero, Spain. Across Spain, volunteer teams of archeologists, anthropologists and forensic scientists head out every year on expeditions to dig for suspected mass graves – a legacy of Spain's fascist past during the time of General Francisco Franco. (Photo by Daniel Ochoa de Olza/AP Photo)

In this March 18, 2015 photo, Andrea, better known as Loira, which is the Portuguese word for “blonde”, poses for a portrait in an open-air crack cocaine market, known as a “cracolandia” or crackland where users can buy crack, and smoke it in plain sight, day or night, in Rio de Janeiro, Brazil. Andrea says she is married and has a home, but she keeps returning to crackland to feed her addiction. (Photo by Felipe Dana/AP Photo)

“DC3 Wreck”. A capture of a US military DC3 plane wreck at the southern black beach in Iceland. Photo location: Iceland. (Photo and caption by Naian Feng/National Geographic Photo Contest)

Fatima Rezai, 21, a female officer from the Afghan National Army (ANA) practices with a punch bag during an exercise session at at the Kabul Military Training Centre (KMTC) in Kabul, Afghanistan October 23, 2016. (Photo by Mohammad Ismail/Reuters)

VIETNAM: A Vietnamese woman, wearing the traditional “ao dai” long dress, poses for photos along peach blossom flowers ahead of the Vietnamese “Tet” (Lunar New Year festival), in a field in Hanoi, Vietnam, February 2, 2016. (Photo by Reuters/Kham)

Police officers display their AI-powered smart glasses in Luoyang, Henan province, China on April 4, 2018. (Photo by Reuters/China Stringer Network)

In this March 2, 2018 photo, an Andean man rests with his llama while tourists take in the natural wonder of Rainbow Mountain in Pitumarca, Peru. Tourists gasp for breath as they climb for two hours to the 16,404-foot (5,000-meter) peak in the Peruvian Andes, but stunned by the magical beauty that unfurls before them. (Photo by Martin Mejia/AP Photo)

A group of teachers and their student use makeshift raft as they cross the street during flood that hit Ranomeeto Barat village in Konawe Selatan, Sulawesi island, Indonesia, July 10, 2018. (Photo by Jojon/Reuters/Antara Foto)