Let X, Tx, N and x be given.
Apply H to the current goal.
Let J be given.
Apply Hexle to the current goal.
Let le be given.
Apply Hexnet to the current goal.
Let net be given.
We prove the intermediate
claim HN:
N = net_pack J le net.
rewrite the current goal using HN (from left to right).
rewrite the current goal using
(net_pack_fun_eq J le net) (from left to right).
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