code: def eth_getUncleCountByBlockNumber(self, block=BLOCK_TAG_LATEST):
          
          block = validate_block(block)
          response = yield from self.rpc_call('eth_getUncleCountByBlockNumber',
                                              [block])
          if response:
              return hex_to_dec(response)
          return response
docs: https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getunclecountbyblocknumber
  
          :param block: Block tag or number (optional)
          :type block: int or BLOCK_TAGS
  
          :return: count
          :rtype: int