def test_get_root_on_create(self):
        root_on_create_val = Instance.get_root_on_create(
            'redis')
        self.assertFalse(root_on_create_val)
def voltage(title, pos, voltage, ax=0):
    """plot voltage vs. position"""
    if ax == 0:
        ax = plt.gca()
    ax.set_title('{} / V'.format(title))
    ax.grid(True)
    ax.plot(pos, voltage)