Function prepare_thresholds 

pub fn prepare_thresholds(
    scale: Option<&Scale>,
) -> Result<(Vec<FloatType>, Vec<Pitch>)>

The thresholds between a scale’s pitches, as fractions of an octave above the octave’s C, and the pitches: music21’s prepareThresholds. The scale is the chromatic scale on C4 where none is given.

Errors

A scale whose pitches cannot be worked out.