code: def get_acl(self, validate=True, headers=None, version_id=None):
          
          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
docs: returns a bucket's acl