code: def on_attribute(self, attr_name, *args, **kwargs):
          
          attr_name = attr_name.upper()
          return super(Parameters, self).on_attribute(attr_name, *args, **kwargs)
docs: Decorator for parameter listeners.
  
          .. note::
  
              There is no way to remove a listener added with this decorator. Use
              :py:func:`add_attribute_listener` if you need to be able to remove
              the :py:func:`listener <remove_attribute_listener>`.
  
          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 code fragment below shows how to get callbacks for the ``THR_MIN`` parameter:
  
          .. code:: python
  
              @vehicle.parameters.on_attribute('THR_MIN')
              def decorated_thr_min_callback(self, attr_name, value):
                  print " PARAMETER CALLBACK: %s changed to: %s" % (attr_name, value)
  
          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.