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)

The newly-discovered gaseous planet Kepler-16b orbits it's two stars. NASA's Kepler Mission discoverd the world orbiting two Stars, the larger a K dwarf and the smaller a red dwarf. (Photo by NASA/JPL-Caltech/T. Pyle via Getty Images)

Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)

Two traditional folk dancers performing in Teheran, Iran. (Photo by Keystone Features/Getty Images). 25th January 1961

Two sailors from HMS Fury enjoy a smoke with two women in bathing suits on a beach in Jersey, where their ship is on a visit. (Photo by William Vanderson/Fox Photos/Getty Images). 29th June 1935

Two elderly men smoking pipes of opium on a terrace in Korea. (Photo by Bert Hardy/Picture Post/Getty Images). August 1950

Two couples prepare to pose for their wedding pictures outside the Forbidden City in Beijing on October 31, 2022. (Photo by Wang Zhao/AFP Photo)

Two cats watch a mouse walking on the pavement in Kuwait City on March 8,2017. (Photo by Yasser Al-Zayyat/AFP Photo)