docs: def upgradeShare1to2(oldShare):
      "Upgrader from Share version 1 to version 2."
      sharedInterfaces = []
      attrs = set(oldShare.sharedAttributeNames.split(u','))
      for iface in implementedBy(oldShare.sharedItem.__class__):
          if set(iface) == attrs or attrs == set('*'):
              sharedInterfaces.append(iface)
  
      newShare = oldShare.upgradeVersion('sharing_share', 1, 2,
                                         shareID=oldShare.shareID,
                                         sharedItem=oldShare.sharedItem,
                                         sharedTo=oldShare.sharedTo,
                                         sharedInterfaces=sharedInterfaces)
      return newShare