code: def getDatabaseFileSize(self):
      
      if DISABLE_PERSISTENT_CACHING:
        return "?"
      size = os.path.getsize(self.__db_filepath)
      if size > 1000000000:
        size = "%0.3fGB" % (size / 1000000000)
      elif size > 1000000:
        size = "%0.2fMB" % (size / 1000000)
      elif size > 1000:
        size = "%uKB" % (size // 1000)
      else:
        size = "%uB" % (size)
      return size
docs: Return the file size of the database as a pretty string.