def append_on_chord(self, on_chord, root):
        """ 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
        """
        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)
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