This line of codes call "receiveApproval()" which is not included in this project/repo.
I assume the contract and the function are existing somewhere, but they are not under auditing this time.
And according to Solidity 0.4.20 documentation, bytes32 is redundant.
https://github.com/tikonoff/staking-app/blob/8306bb8deebe0f554e99bf4e525ea4a3f5672397/contracts/HumanStandardToken.sol#L54
This line of codes call "receiveApproval()" which is not included in this project/repo. I assume the contract and the function are existing somewhere, but they are not under auditing this time. And according to Solidity 0.4.20 documentation,
bytes32
is redundant.