code: def add_attribute_listener(self, attr_name, *args, **kwargs):
          
          attr_name = attr_name.upper()
          return super(Parameters, self).add_attribute_listener(attr_name, *args, **kwargs)
docs: Add a listener callback on a particular parameter.
  
          The callback can be removed using :py:func:`remove_attribute_listener`.
  
          .. note::
  
              The :py:func:`on_attribute` decorator performs the same operation as this method, but with
              a more elegant syntax. Use ``add_attribute_listener`` only if you will need to remove
              the observer.
  
          The callback function is invoked only when the parameter changes.
  
          The callback arguments are:
  
          * ``self`` - the associated :py:class:`Parameters`.
          * ``attr_name`` - the parameter name. This can be used to infer which parameter has triggered
            if the same callback is used for watching multiple parameters.
          * ``msg`` - the new parameter value (so you don't need to re-query the vehicle object).
  
          The example below shows how to get callbacks for the ``THR_MIN`` parameter:
  
          .. code:: python
  
              #Callback function for the THR_MIN parameter
              def thr_min_callback(self, attr_name, value):
                  print " PARAMETER CALLBACK: %s changed to: %s" % (attr_name, value)
  
              #Add observer for the vehicle's THR_MIN parameter
              vehicle.parameters.add_attribute_listener('THR_MIN', thr_min_callback)
  
          See :ref:`vehicle_state_observing_parameters` for more information.
  
          :param String attr_name: The name of the parameter to watch (or '*' to watch all parameters).
          :param args: The callback to invoke when a change in the parameter is detected.