def related_field_filter(lst):
    """ given a list of fields, return the ones that are related """

    ret = []
    for f in lst:
        s = str(f)
        if s.find('django.db.models.fields.related') >= 0 or \
                s.find('audit_log.models.fields.LastUserField') >= 0:
            ret.append(f)

    return ret