New in version 2.0.
Get effective time signature of component:
abjad> staff = Staff("c'8 d'8 e'8 f'8")
abjad> contexttools.TimeSignatureMark((4, 8))(staff)
TimeSignatureMark((4, 8))(Staff{4})
abjad> f(staff)
\new Staff {
\time 4/8
c'8
d'8
e'8
f'8
}
abjad> for note in staff:
... note, contexttools.get_effective_time_signature(note)
...
(Note("c'8"), TimeSignatureMark((4, 8))(Staff{4}))
(Note("d'8"), TimeSignatureMark((4, 8))(Staff{4}))
(Note("e'8"), TimeSignatureMark((4, 8))(Staff{4}))
(Note("f'8"), TimeSignatureMark((4, 8))(Staff{4}))
Return time signature mark or none.