Mazewalk is more than cute, it also occurs when encoding trees whose leaves are operations and whose branches are relative context modifications. (where our key optimisation is that we needn't restore contexts in tail position, just as Mazewalk doesn't palindromise its last unary tree)

Consider it as an alternative to the more common strategy of absolutising the modifications onto the leaves in a first tree walk, and then executing all the now-labelled leaves in arbitrary order in a second pass.