<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_cache(taxonomy_id):
 """Return cache for the given taxonomy id. :param taxonomy_id: identifier of the taxonomy :type taxonomy_id: str :return: dictionary object (empty if no taxonomy_id is found), you must not change anything inside it. Create a new dictionary and use set_cache if you want to update the cache! """

    if taxonomy_id in _CACHE:
        ctime, taxonomy = _CACHE[taxonomy_id]

        # check it is fresh version
        onto_name, onto_path, onto_url = _get_ontology(taxonomy_id)
        cache_path = _get_cache_path(onto_name)

        # if source exists and is newer than the cache hold in memory
        if os.path.isfile(onto_path) and os.path.getmtime(onto_path) > ctime:
            current_app.logger.info(
                'Forcing taxonomy rebuild as cached version is newer/updated.'
            )
            return {}  # force cache rebuild

        # if cache exists and is newer than the cache hold in memory
        if os.path.isfile(cache_path) and os.path.getmtime(cache_path) > ctime:
            current_app.logger.info(
                'Forcing taxonomy rebuild as source file is newer/updated.'
            )
            return {}
        current_app.logger.info('Taxonomy retrieved from cache')
        return taxonomy
    return {}