def compute(self):        
        self.observer = self.force_get_input('Observer')
        self.handler = self.force_get_input('Handler', '')
        self.shareddata = self.force_get_input_list('SharedData')
        if len(self.shareddata)==1:
            self.shareddata = self.shareddata[0]
        if self.observer:
            source = urllib.unquote(self.handler)
            observer = self.observer.vtkInstance
            for e in vtkInteractionHandler.vtkEvents:
                f = e[0].lower() + e[1:]
                f = f.replace('Event', 'Handler')
                source += ('\nif locals().has_key("%s"):\n' % f +
                           '\tobserver.AddObserver("%s", ' % e +
                           'self.eventHandler)\n')
            exec(source)
            if hasattr(self.observer.vtkInstance, 'PlaceWidget'):
                self.observer.vtkInstance.PlaceWidget()
        self.set_output('Instance', self)
Return rId of external relationship of *reltype* to *target_ref*,
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/packages/vtk/vtkhandler.py/vtkInteractionHandler.compute--crossover with--dataset/ETHPy150Open scanny/python-pptx/pptx/opc/package.py/RelationshipCollection.get_or_add_ext_rel