code: def set_acl(self, acl_or_str, key_name='', headers=None, version_id=None):
           
          if isinstance(acl_or_str, Policy):
              raise InvalidAclError('Attempt to set S3 Policy on GS ACL')
          elif isinstance(acl_or_str, ACL):
              self.set_xml_acl(acl_or_str.to_xml(), key_name, headers=headers)
          else:
              self.set_canned_acl(acl_or_str, key_name, headers=headers)
docs: sets or changes a bucket's acl. 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.