New in version 2.0.
Calculate melodic chromatic interval-class from pitch_carrier_1 to pitch_carrier_2:
abjad> pitchtools.calculate_melodic_chromatic_interval_class_from_pitch_carrier_to_pitch_carrier(pitchtools.NamedChromaticPitch(-2), pitchtools.NamedChromaticPitch(12))
MelodicChromaticIntervalClass(+2)
Return melodic chromatic interval-class.