Description:
[Convenience constraint] Constraints the chord root progression of consecutive chords, but different values of `progression' set different variants of Schoenbergs rule set. Supported values for `progression' are as follows.
- :ascending - only ascending chord progressions are permitted
- (:resolve-descending-progression &rest args) - descending progressions are resolved (arguments to rule resolve-descending-progression can be given as further values in this list)
- :harmonic-band - consecutive chords must share common pitch classes
- :common-pcs - consecutive chords must share common pitch classes
Args:
- chord-voice (int): the voice representing the underlying chord.
- n (int): only the first n pitch classes of chords are taken into account, if this argument is set.
Music representation convention:
- A chord/spectrum/scale is represented as a list of pitches or pitch classes
- Pitches are represented as MIDI note numbers, pitch classes as an integers between 0 and 11 (currently limited to 12-TET)
- The root of a chord/spectrum/scale is its first pitch (class)
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