New in version 2.0.
List named chromatic pitches in expr:
abjad> t = Staff("c'4 d'4 e'4 f'4")
abjad> beam = spannertools.BeamSpanner(t[:])
abjad> pitchtools.list_named_chromatic_pitches_in_expr(beam)
(NamedChromaticPitch("c'"), NamedChromaticPitch("d'"), NamedChromaticPitch("e'"), NamedChromaticPitch("f'"))
Return tuple.