code: def get_db_attribute(self, table, record, column, key=None):
          
          if key is not None:
              column = '%s:%s' % (column, key)
          command = ovs_vsctl.VSCtlCommand(
              'get', (table, record, column))
          self.run_command([command])
          if command.result:
              return command.result[0]
          return None
docs: Gets values of 'column' in 'record' in 'table'.
  
          This method is corresponding to the following ovs-vsctl command::
  
              $ ovs-vsctl get TBL REC COL[:KEY]