def transform():
    if component and evt.eventKey:
        try:
            current = float(evt.current)
            totalBytes = int(component.totalBytes())
        except Exception:
            return

        if totalBytes < 1:
            return

        usedPercent, usedBytes, freeBytes = None, None, None

        # SNMP (Platform)
        if 'usedBlocks' in evt.eventKey:
            usedBytes = int(current) * component.blockSize
            usedPercent = (usedBytes / totalBytes) * 100.0
            freeBytes = totalBytes - usedBytes

        # Linux SSH (LinuxMonitor ZenPack)
        elif 'percentUsed' in evt.eventKey:
            usedPercent = current
            usedBytes = totalBytes * (current * 0.01)
            freeBytes = totalBytes - usedBytes

        # Windows (Windows ZenPacks)
        elif 'FreeMegabytes' in evt.eventKey:
            freeBytes = int(current) * 1048576
            usedBytes = totalBytes - freeBytes
            usedPercent = (usedBytes / totalBytes) * 100.0

        else:
            return

        # Make a nicer event summary.
        from Products.ZenUtils.Utils import convToUnits
        evt.summary = "disk space threshold: %3.1f%% used (%s free)" % (
            usedPercent, convToUnits(freeBytes))
        evt.message = evt.summary

transform()