code: def set_canned_acl(self, acl_str, key_name='', headers=None, 
                         version_id=None):
           
          return self.set_canned_acl_helper(acl_str, key_name, headers, 
                                            STANDARD_ACL)
docs: sets or changes a bucket's acl to a predefined (canned) value. 
             We include a version_id argument to support a polymorphic 
             interface for callers, however, version_id is not relevant for 
             Google Cloud Storage buckets and is therefore ignored here.