Function availableTensions

availableTensions(chord: ChordData, scaleName: string): number[]
List a scale's available tensions over a chord.

Available tensions are scale tones that are neither chord tones nor avoid notes, i.e. the usable color tones (typically the 9/11/13 region). The scale is rooted on the chord root. If the scale does not contain the chord, there are no available tensions.
Parameters
- chord: ChordData
  The chord providing the chord tones.
- scaleName: string
  A key of NAMED_SCALES.
Returns number[]
The available-tension pitch classes, sorted ascending in [0, 11].
Example
```
import { makeChord, availableTensions } from '@libraz/libcantus';
availableTensions(makeChord(0, 'maj7'), 'ionian'); // [2, 9] — color tones over Cmaj7
```
- Defined in theory/chordscale/index.ts:194