eapply nd_comp; [ idtac | eapply nd_rule; apply z ].
clear z.
- set (@factorContextRightAndWeaken'' Γ Δ pctx ξ' (eLetRecContext branches,,expr2antecedent body)) as q'.
+ set (@factorContextLeftAndWeaken'' Γ Δ pctx ξ' (eLetRecContext branches,,expr2antecedent body)) as q'.
unfold passback in *; clear passback.
unfold pctx in *; clear pctx.
set (q' disti) as q''.