def METHOD_NAME(self, loop_device):
    # Write some data to the device.
    with directio.open(loop_device.path, "r+") as f:
        f.write(DATA * 2)
    # Zero bytes at the start of the device.
    blockdev.zero(loop_device.path, size=len(ZERO))
    # Verify that the area was zeroed.
    with directio.open(loop_device.path) as f:
        data = f.read(len(ZERO))
        assert data == ZERO
        data = f.read(len(DATA))
        assert data == DATA