How to use the nanogui.Meter function in nanogui

def __init__(self, x, text):
        CWriter.set_textpos(ssd, 0, 0)  # In case previous tests have altered it
        wri = CWriter(ssd, arial10, GREEN, BLACK, verbose=False)
        wri.set_clip(True, True, False)
        super().__init__(wri, 5, x, divisions = 4, ptcolor=YELLOW, label=text,
                         style=Meter.BAR, legends=('0.0', '0.5', '1.0'))
        self.led = LED(wri, ssd.height - 16 - wri.height, x, bdcolor=YELLOW, label ='over')
        self.task = asyncio.create_task(self._run())

async def meter(n, x, text, t):
    print('Meter {} test.'.format(n))
    m = Meter(wri, 5, x, divisions = 4, ptcolor=YELLOW,
              label=text, style=Meter.BAR, legends=('0.0', '0.5', '1.0'))
    l = LED(wri, ssd.height - 16 - wri.height, x, bdcolor=YELLOW, label ='over')
    while True:
        v = int.from_bytes(uos.urandom(3),'little')/16777216
        m.value(v, color(v))
        l.color(color(v))
        l.text(txt(v), fgcolor=color(v))
        refresh(ssd)
        await asyncio.sleep_ms(t)

from writer import CWriter
from nanogui import LED, Meter, refresh
refresh(ssd)

# Fonts
import arial10, freesans20

GREEN = SSD.rgb(0, 255, 0)
RED = SSD.rgb(255, 0, 0)
YELLOW = SSD.rgb(255, 255, 0)
BLACK = 0

color = lambda v : RED if v > 0.7 else YELLOW if v > 0.5 else GREEN
txt = lambda v : 'ovr' if v > 0.7 else 'high' if v > 0.5 else 'ok'

class MyMeter(Meter):
    def __init__(self, x, text):
        CWriter.set_textpos(ssd, 0, 0)  # In case previous tests have altered it
        wri = CWriter(ssd, arial10, GREEN, BLACK, verbose=False)
        wri.set_clip(True, True, False)
        super().__init__(wri, 5, x, divisions = 4, ptcolor=YELLOW, label=text,
                         style=Meter.BAR, legends=('0.0', '0.5', '1.0'))
        self.led = LED(wri, ssd.height - 16 - wri.height, x, bdcolor=YELLOW, label ='over')
        self.task = asyncio.create_task(self._run())

    async def _run(self):
        while True:
            v = int.from_bytes(uos.urandom(3),'little')/16777216
            self.value(v, color(v))
            self.led.color(color(v))
            self.led.text(txt(v), fgcolor=color(v))
            # Slow asynchronous data acquisition might occur here. Note

async def meter(n, x, text, t):
    print('Meter {} test.'.format(n))
    m = Meter(wri, 5, x, divisions = 4, ptcolor=YELLOW,
              label=text, style=Meter.BAR, legends=('0.0', '0.5', '1.0'))
    l = LED(wri, ssd.height - 16 - wri.height, x, bdcolor=YELLOW, label ='over')
    while True:
        v = int.from_bytes(uos.urandom(3),'little')/16777216
        m.value(v, color(v))
        l.color(color(v))
        l.text(txt(v), fgcolor=color(v))
        refresh(ssd)
        await asyncio.sleep_ms(t)