def METHOD_NAME(self):
    net = op.network.Demo()
    o2 = op.phase.Species(network=net, species='o2', name='pure_O2')
    n2 = op.phase.Species(network=net, species='n2', name='pure_N2')
    air = op.phase.GasMixture(network=net, components=[n2, o2])
    air['pore.mole_fraction.pure_N2'] = 0.79
    air['pore.mole_fraction.pure_O2'] = 0.21
    h = air.check_mixture_health()
    assert h.health is True
    air['pore.mole_fraction.pure_O2'] = 0.25
    h = air.check_mixture_health()
    assert h.health is False