def METHOD_NAME(self) -> None:
    """Is the rotation is identity for 1 atom?"""
    a1 = self.a[:1]
    b1 = self.b[:1]
    if hasattr(self.r, "as_matrix"):
        numpy.testing.assert_allclose(numpy.eye(3), utils.get_rotation(a1, b1).as_matrix(), atol=self.delta)
    else:
        numpy.testing.assert_allclose(numpy.eye(3), utils.get_rotation(a1, b1).as_dcm(), atol=self.delta)