New in version 2.0.
Calculate harmonic counterpoint interval pitch_carrier_1 to pitch_carrier_2:
abjad> pitchtools.calculate_harmonic_counterpoint_interval_from_named_chromatic_pitch_to_named_chromatic_pitch(pitchtools.NamedChromaticPitch(-2), pitchtools.NamedChromaticPitch(12))
HarmonicCounterpointInterval(9)
Return harmonic counterpoint interval-class.