New in version 2.0.
True when expr is a sequence and all elements in expr are notehead-assignable integers:
abjad> from abjad.tools import sequencetools
abjad> sequencetools.all_are_assignable_integers([1, 2, 3, 4, 6, 7, 8, 12, 14, 15, 16])
True
True when expr is an empty sequence:
abjad> sequencetools.all_are_assignable_integers([])
True
False otherwise:
abjad> sequencetools.all_are_assignable_integers('foo')
False
Return boolean.