'Sets or updates a bucket\'s default object acl to a predefined
(canned) value.'

def set_def_canned_acl(self, acl_str, validate=False, headers=None, version_id=None):

    self._check_bucket_uri('set_def_canned_acl    ')
    key = self.get_key(validate, headers)
    self.check_response(key, 'key', self.uri)
    key.set_def_canned_acl(acl_str, headers, version_id)
