docs: def _check_data_port_id(self, data_port):
          """Checks the validity of a data port id
  
          Checks whether the id of the given data port is already used by anther data port (input, output, scoped vars)
          within the state.
  
          :param rafcon.core.data_port.DataPort data_port: The data port to be checked
          :return bool validity, str message: validity is True, when the data port is valid, False else. message gives
              more information especially if the data port is not valid
          """
          # First check inputs and outputs
          valid, message = super(ContainerState, self)._check_data_port_id(data_port)
          if not valid:
              return False, message
          # Container state also has scoped variables
          for scoped_variable_id, scoped_variable in self.scoped_variables.items():
              if data_port.data_port_id == scoped_variable_id and data_port is not scoped_variable:
                  return False, "data port id already existing in state"
          return True, message