have hstart' : start < stop := Nat.lt_of_le_of_ne hstart hne
α : Type u_1
as bs : Array α
start stop i : Nat
hstart : start ≤ stop
hstop : stop ≤ bs.size
hi : i < as.size
h : i < (foldl push as bs start stop).size
hne : ¬start = stop
⊢ (foldl push as bs start stop)[i] = as[i]
α : Type u_1
as bs : Array α
start stop i : Nat
hstart : start ≤ stop
hstop : stop ≤ bs.size
hi : i < as.size
h : i < (foldl push as bs start stop).size
hne : ¬start = stop
hstart' : start < stop
⊢ (foldl push as bs start stop)[i] = as[i]