Joe Deedon, president of TAC ONE Consulting, demonstrates searching for a shooter in a middle school during an Active Shooter Response course offered by TAC ONE in Denver April 2, 2016. According to TAC ONE, the course, which is offered for the first time to concealed weapons permit carrying civilians, is designed at preparing people to effectively save lives prior to the arrival of law enforcement at an active shooter incident. (Photo by Rick Wilking/Reuters)

A woman sits on a terrace at Tiki hostel in Cantagalo favela, in Rio de Janeiro, Brazil, April 16, 2016. Hostels in a few of Rio's more than 1,000 slums serve not only as a cheap housing alternative for the more adventurous among the estimated 500,000 foreign tourists expected to arrive for the Olympics in August. The establishments also open up the rich culture of the city's shantytowns for travellers, giving them a glimpse into once “no-go” areas where about one-fifth of Rio's population lives. (Photo by Pilar Olivares/Reuters)

A migrant holds a placard which reads “No Forced Deportations” as he rides his bicycle at the makeshift camp called “The New Jungle” in Calais, France, September 18, 2015. Around 3,500 migrants and refugees are camped in Calais, fleeing war and poverty in the Middle East, Africa and Asia and now living in the jungle. Most of them are hoping to make the crossing to England. (Photo by Regis Duvignau/Reuters)

Project Mermaids model. Project Mermaids lets ocean-lovers don tails and live out their siren fantasies. Clients can pay for a shoot that is either on land or underwater, with the images looking to raise awareness about preservation of beaches, seas and oceans. The project – which is shot by photographers Angelina Venturella and Chiara Salomoni – started purely to raise awareness, with celebrities dressing up as sirens as part of the cause. (Photo by Angelina Venturella/Chiara Salomoni/Caters News Agency)

Zahra Lari runs in a scene shot for the Nike Middle East ad campaign filmed in Dubai, UAE, February 10, 2017. An online commercial released by Nike (NKE.N) this week that showed Arab women fencing, boxing and spinning on ice-skates has stirred controversy over its attempt to smash stereotypes about women leading home-bound lives in the conservative region. (Photo by Reuters/Nike)

Festivalgoers dance during the Balaton Sound music festival in Zamardi, Hungary, July 5, 2018. Balaton Sound is one of Europe's largest open air electronic music festivals. Held annually since 2007 on the southern bank of Lake Balaton, Hungary, it features live acts and DJ's from all around the world, from established artists to new names. The event was co-created by the organizers of Sziget Festival. (Photo by Bernadett Szabo/Reuters)

A boy poses for a photo as he plays with a homemade toy gun in Qayara, south of Mosul, Iraq, Tuesday, November 22, 2016. For months, residents of the Iraqi town of Qayara have lived in the darkness from a cloud of toxic fumes released by oil fields lit by retreating Islamic State fighters. (Photo by Felipe Dana/AP Photo)

The People of Mah Meri tribe at home at Pulau Carey village on December 03, 2016 in Selangor, Malaysia. The Mah Meri people are one 18 tribes of Orang Asal (indigenous people) living in west Malaysia. The Mah Meri are know for thei wood carvings and also for the richness of their songs and dances. (Photo by Yuli Seperi/Sijori Images/Barcroft India)