Apply unknownprop_18c079d0a948e2707cbd31a4293ae2dc77179c2184f0225dd81bf201082f253d with
u17_to_Church17,
u4,
λ x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 x13 x14 x15 x16 . x4.
The subproof is completed by applying unknownprop_d7ad1375eb52af4879596ebc7028440ca9d92c168027145243d18b8cf1b612f5.