def METHOD_NAME(self):
    """
    Non-composite system, operator on Liouville space.
    """
    tol = 1e-12
    rho_3 = rand_dm(3)
    superop = kraus_to_super(rand_kraus_map(3))
    analytic_result = vector_to_operator(superop @
                                         operator_to_vector(rho_3))
    naive_result = subsystem_apply(rho_3, superop, [True],
                                   reference=True)
    naive_diff = (analytic_result - naive_result).full()
    naive_diff_norm = norm(naive_diff)
    assert naive_diff_norm < tol
    efficient_result = subsystem_apply(rho_3, superop, [True])
    efficient_diff = (efficient_result - analytic_result).full()
    efficient_diff_norm = norm(efficient_diff)
    assert efficient_diff_norm < tol