It is a simple chord transposer. The chords can be mixed with song lyrics the function will identify what represents a chord and what does not.
chord_sub("C9 G/B Gm6(11)", 7) # 7 semitones shiffted
return -- > "G9 D/F# Dm6(11)"
www.online-python.com/ktQ1RKIraV (link content not updated)