An Afghan National Army (ANA) soldier assigned to the Mobile Strike Force Kandak fires a RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, May 20, 2013. The Marines with the Mobile Strike Force Advisor Team instructed and mentored their ANA counterparts on how to properly utilize their weapons systems. (Photo by SSgt Ezekiel R. Kitandwe/RCT 7)

A woman smokes a mask bong on the final day of Hempfest, Seattle's annual gathering to promote the legalization of marijuana, on August 17, 2014. (Photo by Jordan Stead/Seattlepi.com)

A photo taken on August 29, 2014, shows Mount Tavurvur erupting in eastern Papua New Guinea, spewing rocks and ash into the air, forcing the evacuation of local communities and international flights to be re-routed. Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, rumbled to life early in the morning on the tip of the remote island of New Britain. (Photo by Oliver Bluett/AFP Photo)

A bear that wandered into a University of Colorado Boulder dorm complex falls from a tree after being tranquilized by Colorado wildlife officials on April 26, 2012. Colorado wildlife official Jennifer Churchill said that the 200-pound male bear was tagged and relocated to a remote Rocky Mountain area. The bear was hit by two cars on May 3 and died. (Photo by Andy Duann)

In this April 4, 2017 photo keeper German Alonso straps a leg prothesis to on the left leg of secretarybird Soeckchen (Sagittarius seprentarius) at the bird park in Walsrode, northern Germany. The prothesis was made in a 3D-printer after his left leg was amputated. (Photo by Philipp Schulze/DPA via AP Photo)

Soldiers take part in a drill during a heavy snow in Heihe, Heilongjiang province, February 26, 2014. (Photo by Reuters/China Daily)

An American flag is visible in the windows of the cupola aboard the International Space Station. Thanks to a bill passed by Texas legislators in 1997 that put in place technical voting procedure for astronauts – nearly all of whom live in Texas – they have the ability to vote from space through specially designed absentee ballots. To preserve the integrity of the secret vote, the ballot is encrypted and only accessible by the astronaut and the county clerk responsible for casting the ballot. (Photo by NASA)

In this April 20, 2017 photo, a woman is aided by fellow demonstrators after falling, overcome by tear gas, during anti-government protests in Caracas, Venezuela. Tens of thousands of protesters asking for the resignation of President Nicolas Maduro flooded the streets again, one day after three people were killed and hundreds arrested in the biggest anti-government demonstrations in years. (Photo by Ariana Cubillos/AP Photo)