def wanmen_download_by_course_topic(json_api_content, tIndex, output_dir='<STR_LIT:.>', merge=True, info_only=False, **kwargs):
for pIndex in range(len(json_api_content[<NUM_LIT:0>]['<STR_LIT>'][tIndex]['<STR_LIT>'])):<EOL><INDENT>wanmen_download_by_course_topic_part(json_api_content,<EOL>tIndex,<EOL>pIndex, <EOL>output_dir=output_dir,<EOL>merge=merge,<EOL>info_only=info_only,<EOL>**kwargs)<EOL><DEDENT>
int, int->None

    Download a TOPIC of a course.
    Reuse the API call to save time.