bugfix and doc clarification. fix test.
bugfix and doc clarification. fix test.

ruchevits/solidity,ruchevits/solidity,ruchevits/solidity,arkpar/solidity,debris/solidity,chriseth/solidity-doc-test,chriseth/solidity,LianaHus/solidity,douglas-larocca/solidity,ruchevits/solidity,vaporry/solidity,ethers/solidity,gluk256/solidity,shahankhatch/solidity