Chords for BTS - GOGO, 방탄소년단 - 고민보다 GO (Heart Perfomance for ARMY♥_♥) @2017 MBC Music Festival (). Spark is the smartest and most interesting app to learn and enjoy playing guitar. Spark is an all-around app for beginners and advanced players to learn any song with chords or master new skills with hundreds of lessons and games in Spark.