with g.currentState() as current:

        allPages = sorted(current.subjects(RDF.type, L9.FadePage), key=lambda fp: str(fp))

        mapping = getGraphMappingNode(current)

        curPage = current.value(mapping, L9.outputs)

    if curPage is None:

        curPage = allPages[0]

    idx = allPages.index(curPage)

    newIdx = clamp(idx + dp, 0, len(allPages) - 1)

    print('change from ', idx, newIdx)

    newPage = allPages[newIdx]

    setCurMappedPage(g, mapping, newPage)

def writeHwValueToGraph(graph: SyncedGraph, ctx, fader: URIRef, strength: float):

    log.info(f'setFader(fader={fader}, strength={strength:.03f}')

    valueLit = decimalLiteral(round(strength, 3))

    with graph.currentState() as g:

        fadeSet = g.value(fader, L9['setting'])

    if fadeSet is None:

        raise ValueError(f'fader {fader} has no :setting')

    graph.patchObject(ctx, fadeSet, L9['value'], valueLit)

def onMessage(graph: SyncedGraph, ctx: URIRef, m: Dict):

    if m['type'] == 'active_sensing':

        return

    if m['type'] == 'control_change':

        if m['dev'] == 'bcf2000' and m['control'] == 91:

            changePage(graph, -1)

            return

        if m['dev'] == 'bcf2000' and m['control'] == 92:

            changePage(graph, 1)

            return

        try:

            fader = {

                'quneo': {

                    44: L9['show/dance2023/fadePage1f0'],

                    45: L9['show/dance2023/fadePage1f0'],

                    46: L9['show/dance2023/fadePage1f0'],

                },

                'bcf2000': currentFaders,

            }[m['dev']][m['control']]

        except KeyError:

            log.info(f'unknown control {m}')

            return

        try:

            writeHwValueToGraph(graph, ctx, fader, m['value'] / 127)

            _lastSet[m['control']] = m['value']

        except ValueError as e:

            log.warning(f'{e!r} - ignoring')

    else:

        log.info(f'unhandled message {m}')

def reduceToLatestValue(ms: List[Dict]) -> List[Dict]:

    merge = {}