code: def __verify_db_file_existence(self, database_path):
          
  
          self.__validate_db_path(database_path)
          if not os.path.isfile(os.path.realpath(database_path)):
              raise IOError("file not found: " + database_path)
  
          try:
              connection = sqlite3.connect(database_path)
          except sqlite3.OperationalError as e:
              raise OperationalError(e)
  
          connection.close()
docs: :raises SimpleSQLite.OperationalError: If unable to open database file.