def error(message, level="error", exit_code=1, **kwargs):
    kwargs["fg"] = kwargs.get("fg", "red")
    click.secho(u"error: {}".format(message), **kwargs)
    sys.exit(exit_code)
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)