<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def reload_index(self, progress_cb=dummy_progress_cb):
 """ Read the index, and load the document list from it Arguments: callback --- called during the indexation (may be called *often*). step : DocSearch.INDEX_STEP_READING or DocSearch.INDEX_STEP_SORTING progression : how many elements done yet total : number of elements to do document (only if step == DocSearch.INDEX_STEP_READING):
 file being read """

        nb_results = self.index.start_reload_index()
        progress = 0
        while self.index.continue_reload_index():
            progress_cb(progress, nb_results, self.INDEX_STEP_LOADING)
            progress += 1
        progress_cb(1, 1, self.INDEX_STEP_LOADING)
        self.index.end_reload_index()