contract MoreSecureRand {

    modifier onlyEOA {
        address caller = msg.sender;
        uint size;
        assembly {
            size := extcodesize(caller)
        }
        require(size == 0);
        _;
    }

    function rand() public view onlyEOA returns (uint)  {
        uint blockNo = block.number - 1;
        uint random_number = uint(block.blockhash(blockNo)) % 10 + 1;
        return random_number;
    }

}