for dc in graph.subjects(RDF.type, L9['DeviceClass']):

        log.info('mapping DeviceClass %s', dc)

        for dev in graph.subjects(RDF.type, dc):

            dev = cast(DeviceUri, dev)

            log.info('  mapping device %s', dev)

            universe = cast(OutputUri, graph.value(dev, L9['dmxUniverse']))

            try:

                output = outputByUri[universe]

            except Exception:

                log.warn('dev %r :dmxUniverse %r', dev, universe)

                raise

            for row in graph.objects(dc, L9['attr']):

                outputAttr = cast(OutputAttr,

                                  graph.value(row, L9['outputAttr']))

                offset = DmxIndex(

                    cast(Literal, graph.value(row, L9['dmxOffset'])).toPython())

                index = DmxMessageIndex(dmxBase + offset - 1)

                ret[(dev, outputAttr)] = (output, index)

                log.debug('    map %s to %s,%s', outputAttr, output, index)

    return ret

class Collector:

                        (self.shortId(), ' '.join(map(str, buf[:16]))))

                sent = self.dev.send_multi_value(1, buf)

                if sent != len(buf):

                    raise ValueError("incomplete send")

            except usb.core.USBError as e:

                # not in main thread

                if e.errno == 75:

                    self._writeOverflow += 1

                    return

                msg = 'usb: sending %s bytes to %r; error %r' % (len(buf),

                                                                 self.uri, e)

                log.warn(msg)

                raise

'''

# the code used in 2018 and before

class UdmxOld(BackgroundLoopOutput):

    def __init__(self, uri, bus):

        from light9.io.udmx import Udmx