Task: Question Answering
Input (English): Passage: On August 9, 2015, ESPN reported that the New Orleans VooDoo and Las Vegas Outlaws had ceased operations, effective immediately, a claim which was subsequently validated on the AFL website. On September 1, 2015, the Spokane Shock officially left the AFL and joined the IFL under the new name Spokane Empire, becoming the fifth active AFL/af2 franchise to leave for the IFL since bankruptcy (Iowa Barnstormers, Tri-Cities Fever, Green Bay Blizzard and Arkansas Twisters—now the Texas Revolution—left previously). Question: On what date did the Spokane Shock leave the AFL?
Output (English): September 1, 2015