Function output 

pub fn output<CTX, HALTREASON>(
    context: &mut CTX,
    result: FrameResult,
) -> ResultAndState<HALTREASON>
where
    CTX: ContextTr,
    <CTX as ContextTr>::Journal: JournalTr<FinalOutput = JournalOutput>,
    HALTREASON: HaltReasonTr,

Calculate last gas spent and transform internal reason to external.

TODO make Journal FinalOutput more generic.