New in version 1.1.
True when expr is assignable rational. Otherwise false:
abjad> from abjad.tools import durationtools
abjad> for numerator in range(0, 16 + 1):
... duration = Fraction(numerator, 16)
... print '%s\t%s' % (duration, durationtools.is_assignable_rational(duration))
...
0 False
1/16 True
1/8 True
3/16 True
1/4 True
5/16 False
3/8 True
7/16 True
1/2 True
9/16 False
5/8 False
11/16 False
3/4 True
13/16 False
7/8 True
15/16 True
1 True
Return boolean.
Changed in version 2.0: renamed durationtools.is_assignable() to durationtools.is_assignable_rational().