def METHOD_NAME(self):
    pn = op.network.Demo()
    phase = op.phase.Species(network=pn, species='oxygen')
    argmap = op.models.phase.default_argmap
    vals = {
        'Stiel_Thodos': op.models.phase.viscosity.gas_pure_st,
        'viscosity_gas_Gharagheizi': op.models.phase.viscosity.gas_pure_gesmr,
    }
    for k, v in vals.items():
        print(f'Testing {k}')
        f = getattr(chemicals.viscosity, k)
        args = inspect.getfullargspec(f)[0]
        kwargs = {i: np.atleast_1d(phase[argmap[i]])[0] for i in args}
        ref = f(**kwargs)
        val = v(phase)[0]
        assert_allclose(ref, val, rtol=1e-13)