def change_hit_type_of_hit(self, hit_id, hit_type):
        """
        Change the HIT type of an existing HIT. Note that the reward associated
        with the new HIT type must match the reward of the current HIT type in
        order for the operation to be valid.
        
        :type hit_id: str
        :type hit_type: str
        """
        params = {'HITId' : hit_id,
                  'HITTypeId': hit_type}

        return self._process_request('ChangeHITTypeOfHIT', params)