GraphProxy.sol#L140
In GraphProxy.sol#L140, there is a local variable named _pendingImplementation, but there is a function named _pendingImplementation() in the inherited GraphProxyStorage with the same name. This use causes compilers to issue warnings, negatively affecting checking and code readability. 
Avoid using variables with the same name, including inherited in the same contract, if used, it must be specified in the NatSpec comments.
