Seems strange that Ðe is implemented as "apply f to in to make out and then yield [in[1],out[2],in[3],out[4],...]" rather than as "yield [in[1],f(in[2]),in[3],f(in[4]),...]")
i.e.: I'd expect ṚÐe applied to [[[0,1],2,3],[4,5,[6,7],[8,9]]] to yield [[[0,1],2,3],[[8,9],[6,7],5,4]] not [[[0,1],2,3],[[0,1],2,3]] but for that we need Ṛ€Ðe
