Figure out mapping & binding

[supposedly]

N..E (1, 2, 3), [N: (3, 2, 1)]
# should produce
(1, 2, 3), (1, 2, 3), (1, 2, 3), [N: (3, 2, 1)]
# and then become
1, (1, 2, 3), (1, 2, 3), 3
2, (1, 2, 3), (1, 2, 3), 2
3, (1, 2, 3), (1, 2, 3), 1

and

N..E [(1, 2, 3)], [N: (3, 2, 1)]
# should produce
(1, 2, 3), [N], [N], [N: (3, 2, 1)]
# and then become
1, 1, 3
2, 2, 2
3, 3, 1

Currently I have it so that only the latter happens in both scenarios, which I don't think is right. The second stage is properly reached, but then after that the [N] bindings get expanded to their variables too soon, destroying the distinction (and I'm not sure how to fix it without reordering everything -- see the if v == ... listcomp lines)

[supposedly]

...apparently it does do this properly but I'm not sure how