def get_acl(self, validate=True, headers=None, version_id=None):
        """returns a bucket's acl"""
        if not self.bucket_name:
            raise InvalidUriError('get_acl on bucket-less URI (%s)' % self.uri)
        bucket = self.get_bucket(validate, headers)
        # This works for both bucket- and object- level ACLs (former passes
        # key_name=None):
        acl = bucket.get_acl(self.object_name, headers, version_id)
        self.check_response(acl, 'acl', self.uri)
        return acl
returns a bucket's acl