code: def deleteItem(self, itemID):
          
          collections = self.get_data_collections()
  
          query = {"currentMax": {"$exists": True}}
          currentMax = self.noteDB["IDs"].find_one(query)['currentMax']
          query = {"unusedIDs": {"$exists": True}}
          unusedIDs = self.noteDB['IDs'].find_one(query)['unusedIDs']
  
          if (itemID > currentMax) or (itemID in unusedIDs):
              raise ValueError("ID {0} does not exist".format(itemID))
  
          # Find document with ID
          for coll in collections:
              self.noteDB[coll].remove({"ID": itemID})
  
          if currentMax == itemID:
              self.noteDB['IDs'].update({"currentMax": currentMax},
                                        {"currentMax": currentMax - 1})
          else:
              unusedIDs.append(itemID)
              self.noteDB['IDs'].update({"unusedIDs": {"$exists": True}},
                                        {"unusedIDs": unusedIDs})
  
          return itemID
docs: :desc: Deletes item with ID = itemID, takes care of IDs collection
             :param itemID: The item ID to delete
             :type itemID: int
             :raises: ValueError
             :returns ID: The ID of the deleted item
             :rval: int