In the Level 2 beginner lesson "Let's Test the Formula ... Sus 4 Chords," Lisa discusses a Gsus4 chord, but the accompanying notation says "Gadd4". The notation in fact adds a C, but the B is still there, and this also seems to be what Lisa is saying to do. Is this a mistake, or am I missing something? How did we go from a "sus" to an "add." Thank you.