<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_contents(brain_or_object):
 """Lookup folder contents for this object. :param brain_or_object: A single catalog brain or content object :type brain_or_object: ATContentType/DexterityContentType/CatalogBrain :returns: List of contained contents :rtype: list/Products.ZCatalog.Lazy.LazyMap """


    # Nothing to do if the object is contentish
    if not is_folderish(brain_or_object):
        return []

    # Returning objects (not brains) to make sure we do not miss any child.
    # It may happen when children belong to different catalogs and not
    # found on 'portal_catalog'.
    ret = filter(lambda obj: api.is_object(obj),
                 api.get_object(brain_or_object).objectValues())
    return ret