code: def append_on_chord(self, on_chord, root):
          
          root_val = note_to_val(root)
          on_chord_val = note_to_val(on_chord) - root_val
  
          list_ = list(self.components)
          for idx, val in enumerate(list_):
              if val % 12 == on_chord_val:
                  self.components.remove(val)
                  break
  
          if on_chord_val > root_val:
              on_chord_val -= 12
  
          if on_chord_val not in self.components:
              self.components.insert(0, on_chord_val)
docs: Append on chord
  
          To create Am7/G
          q = Quality('m7')
          q.append_on_chord('G', root='A')
  
          :param str on_chord: bass note of the chord
          :param str root: root note of the chord