New in version 1.1.
Divide chord by chromatic pitch number:
abjad> chord = Chord(range(12), Duration(1, 4))
abjad> chord
Chord("<c' cs' d' ef' e' f' fs' g' af' a' bf' b'>4")
abjad> chordtools.divide_chord_by_chromatic_pitch_number(chord, pitchtools.NamedChromaticPitch(6))
(Chord("<fs' g' af' a' bf' b'>4"), Chord("<c' cs' d' ef' e' f'>4"))
Input chord may be a note, rest or chord but not a skip.
Zero-length parts return rests, length-one parts return notes and other parts return chords.
Return pair of newly constructed leaves.
Changed in version 2.0: renamed chordtools.split_by_pitch_number() to chordtools.divide_chord_by_chromatic_pitch_number().