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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def remoteIndexer1to2(oldIndexer):
 """ Previously external application code was responsible for adding a RemoteListener to a batch work source as a reliable listener. This precluded the possibility of the RemoteListener resetting itself unilaterally. With version 2, RemoteListener takes control of adding itself as a reliable listener and keeps track of the sources with which it is associated. This upgrader creates that tracking state. """

    newIndexer = oldIndexer.upgradeVersion(
        oldIndexer.typeName, 1, 2,
        indexCount=oldIndexer.indexCount,
        installedOn=oldIndexer.installedOn,
        indexDirectory=oldIndexer.indexDirectory)

    listeners = newIndexer.store.query(
        batch._ReliableListener,
        batch._ReliableListener.listener == newIndexer)

    for listener in listeners:
        _IndexerInputSource(
            store=newIndexer.store,
            indexer=newIndexer,
            source=listener.processor)

    return newIndexer