code: def getUncleByBlock(self, block_identifier, uncle_index):
          
          method = select_method_for_block_identifier(
              block_identifier,
              if_predefined='eth_getUncleByBlockNumberAndIndex',
              if_hash='eth_getUncleByBlockHashAndIndex',
              if_number='eth_getUncleByBlockNumberAndIndex',
          )
          result = self.web3.manager.request_blocking(
              method,
              [block_identifier, uncle_index],
          )
          if result is None:
              raise BlockNotFound(
                  f"Uncle at index: {uncle_index} of block with id: {block_identifier} not found."
              )
          return result
docs: `eth_getUncleByBlockHashAndIndex`
          `eth_getUncleByBlockNumberAndIndex`