Chicago TribuneStoneman Douglas shooting survivors prepare to leave for Florida CapitolChicago TribuneTyra Heman, a senior at Marjory Stoneman Douglas High School, holds a sign that reads, "Enough No Guns" in front of the school where 17 people were killed on Feb. 14, 2018, in Parkland, Fla. (Joe Raedle / Getty Images).