{
    (g)
        /(dequeReduce)
            (x)
                (isEmpty)(lPopped)(lItem)(rPopped)(rItem)
                /
                    //</[lItem]/[x][g]>[dequeReduce][lPopped]
                /
                    [x]
                [isEmpty]
        [YC]
|
    dequeLReduce
}

{
    (g)
        /(dequeReduce)
            (x)
                (isEmpty)(lPopped)(lItem)(rPopped)(rItem)
                /
                    //</[rItem]/[x][g]>[dequeReduce][rPopped]
                /
                    [x]
                [isEmpty]
        [YC]
|
    dequeRReduce
}