def on_change_input(self, fgraph, app, i, old_r, new_r, reason):
        if app == 'output':
            # app == 'output' is special key that means FunctionGraph is redefining which nodes are being
            # considered 'outputs' of the graph.
            pass
        else:
            if app not in self.debug_all_apps:
                raise ProtocolError("change without import")

            # UPDATE self.clients
            self.clients[old_r][app] -= 1
            if self.clients[old_r][app] == 0:
                del self.clients[old_r][app]

            self.clients.setdefault(new_r, OrderedDict()).setdefault(app, 0)
            self.clients[new_r][app] += 1

            # UPDATE self.view_i, self.view_o
            for o_idx, i_idx_list in iteritems(getattr(app.op, 'view_map',
                                                       OrderedDict())):
                if len(i_idx_list) > 1:
                    # destroying this output invalidates multiple inputs
                    raise NotImplementedError()
                i_idx = i_idx_list[0]
                output = app.outputs[o_idx]
                if i_idx == i:
                    if app.inputs[i_idx] is not new_r:
                        raise ProtocolError("wrong new_r on change")

                    self.view_i[output] = new_r

                    self.view_o[old_r].remove(output)
                    if not self.view_o[old_r]:
                        del self.view_o[old_r]

                    self.view_o.setdefault(new_r, OrderedSet()).add(output)

        self.stale_droot = True
app.inputs[i] changed from old_r to new_r.
dataset/ETHPy150Open rizar/attention-lvcsr/libs/Theano/theano/gof/destroyhandler.py/DestroyHandler.on_change_input