'Sets or updates a bucket\'s ACL with an XML string.'

def set_xml_acl(self, xmlstring, key_name='', validate=False, headers=None, version_id=None, if_generation=None, if_metageneration=None):

    self._check_bucket_uri('set_xml_acl')
    key_name = (key_name or self.object_name or '')
    bucket = self.get_bucket(validate, headers)
    if self.generation:
        bucket.set_xml_acl(xmlstring, key_name, headers, generation=self.generation, if_generation=if_generation, if_metageneration=if_metageneration)
    else:
        version_id = (version_id or self.version_id)
        bucket.set_xml_acl(xmlstring, key_name, headers, version_id=version_id)
