New in version 2.0.
Change sequence to degree of rotational symmetry:
abjad> from abjad.tools import sequencetools
abjad> sequencetools.get_sequence_degree_of_rotational_symmetry([1, 2, 3, 4, 5, 6])
1
abjad> sequencetools.get_sequence_degree_of_rotational_symmetry([1, 2, 3, 1, 2, 3])
2
abjad> sequencetools.get_sequence_degree_of_rotational_symmetry([1, 2, 1, 2, 1, 2])
3
abjad> sequencetools.get_sequence_degree_of_rotational_symmetry([1, 1, 1, 1, 1, 1])
6
Return positive integer.