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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 tracker_index():
 """Get tracker overview."""

    stats = server.stats
    if stats and stats.snapshots:
        stats.annotate()
        timeseries = []
        for cls in stats.tracked_classes:
            series = []
            for snapshot in stats.snapshots:
                series.append(snapshot.classes.get(cls, {}).get('sum', 0))
            timeseries.append((cls, series))

        series = [s.overhead for s in stats.snapshots]
        timeseries.append(("Profiling overhead", series))

        if stats.snapshots[0].system_total.data_segment:
            # Assume tracked data resides in the data segment
            series = [s.system_total.data_segment - s.tracked_total - s.overhead
                      for s in stats.snapshots]
            timeseries.append(("Data segment", series))
            series = [s.system_total.code_segment for s in stats.snapshots]
            timeseries.append(("Code segment", series))
            series = [s.system_total.stack_segment for s in stats.snapshots]
            timeseries.append(("Stack segment", series))
            series = [s.system_total.shared_segment for s in stats.snapshots]
            timeseries.append(("Shared memory", series))
        else:
            series = [s.total - s.tracked_total - s.overhead
                      for s in stats.snapshots]
            timeseries.append(("Other", series))
        return dict(snapshots=stats.snapshots, timeseries=timeseries)
    else:
        return dict(snapshots=[])