Return the nonnegative integers i, j, ... for which l[i], l[j], ... are True.
abjad> l = [0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1]
abjad> listtools.true_indices(l)
[3, 4, 5, 9, 10, 11]
abjad> l = [0, 0, 0, 0, 0, 0]
abjad> listtools.true_indices(l)
[]
Raise TypeError when l is neither list nor tuple:
abjad> listtools.true_indices('foo')
TypeError