Saira Liaqat, 22, a victim of acid violence who was burned 4 years ago, poses in Islamabad, June 11, 2007. Saira is from Lahore and was attacked with acid thrown on her over an argument relating to an arranged marriage. (Photo by Paula Bronstein/Getty Images)

People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

Justin Nelzen, in red vest, joins others as they work to rescue up to 70 horses along Cypresswood Drive near Humble along Cypress Creek, Monday, April 18, 2016, in Houston. More than a foot of rain fell Monday in parts of Houston, submerging scores of subdivisions and several major interstate highways, forcing the closure of schools and knocking out power to thousands of residents who were urged to shelter in place. (Photo by Mark Mulligan/Houston Chronicle via AP Photo)

In this photo taken on Saturday, November 16, 2013, Mt. Etna, Europe's most active volcano, spews lava during an eruption as seen from Acireale, near the Sicilian town of Catania, Italy. (Photo by Carmelo Imbesi/AP Photo)

A firefighter battling the King Fire watches as a backfire burns along Highway 50 in Fresh Pond, California September 16, 2014. The fire led officials to call on about 400 people to evacuate from areas threatened by the blaze, Cal Fire spokeswoman Alyssa Smith said. It has charred more than 11,500 acres (4,654 hectares) and was 5 percent contained on Tuesday. (Photo by Noah Berger/Reuters)

Traditional sculptures by Chin tribe in, Mindat, Myanmar, November 2016. In the mountains of Myanmar lives a tribe where the women have taken a unique approach to their beauty regime by decorating their faces with tattoos. The Chin people in the remote mountain town of Mindat, have been marking women in the area with intricate face tattoos for centuries. (Photo by Teh Han Lin/Barcroft Images)

A Palestinian reveller takes part in a colours festival organized by Palestinian activists in the West Bank city of Ramallah August 20, 2015. The festival is inspired by the Hindu spring festival of Holi. (Photo by Mohamad Torokman/Reuters)

Six new Canadians take their oath of citizenship while harnessed on the CN Tower's “Edgewalk” 356 metres (1,168 feet) above Toronto, Ontario, Canada in a still image from video October 9, 2018. (Photo by CN Tower/Handout via Reuters)