def create_id2study_info(path, tag):
    """Searchers for *.json files in this repo and returns
    a map of study id ==> (`tag`, dir, study filepath)
    where `tag` is typically the shard name
    """
    d = {}
    for triple in os.walk(path):
        root, files = triple[0], triple[2]
        for filename in files:
            if filename.endswith('.json'):
                study_id = filename[:-5]
                d[study_id] = (tag, root, os.path.join(root, filename))
    return d