In this August 26, 2019 photo, children of the Nambikwara Sarare tribe climb trees as they play in their indigenous reserve in the southwestern Amazon, near Conquista D'Oeste, in the Brazilian state of Mato Grosso. About 98% of all Brazil’s indigenous lands lie within the Amazon. (Photo by Andre Penner/AP Photo)

A U.S. Army crew chief flying on board a CH-47F Chinook helicopter observes the successful test of flares during a training flight in Afghanistan, March 14, 2018. (Photo by Tech. Sgt. Gregory Brook/Reuters/U.S. Air Force)

Central Palo Seco power station of the Puerto Rico Electric Power Authority (PREPA) is seen behind a cemetery, in San Juan, Puerto Rico on January 22, 2018. (Photo by Alvin Baez/Reuters)

A young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

Opposition students march against Venezuelan President Nicolas Maduro's government in Caracas February 12, 2015. Venezuelan troops blocked students during marches against Maduro on Thursday as pro-government supporters also rallied on the anniversary of 2014 protests that led to 43 deaths. In Caracas, troops cordoned off scores of students on an unauthorized march to a church where they planned a mass in honour of demonstrators who died. (Photo by Jorge Silva/Reuters)

This September 22, 2014 photo, shows a building with street art murals in the Santurce neighborhood in San Juan, Puerto Rico. (Photo by Ricardo Arduengo/AP Photo)

Prospective flight attendants listen to their instructor during an etiquette training course at Indigo Airlines' Ifly training centre in Gurgaon on the outskirts of New Delhi November 18, 2014. (Photo by Adnan Abidi/Reuters)