New in version 2.5.
Get leaf in expr with minimum prolated duration:
abjad> staff = Staff("c'4.. d'16 e'4.. f'16")
abjad> leaftools.get_leaf_in_expr_with_minimum_prolated_duration(staff)
Note("d'16")
When two leaves in expr are both of equally minimal prolated duration, return the first leaf encountered in forward iteration.
Return none when expr contains no leaves:
abjad> leaftools.get_leaf_in_expr_with_minimum_prolated_duration([]) is None
True
Return leaf.