rw [get_push_lt]
case right
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
this✝ : start < bs.size
this : i < (foldl push (as.push bs[start]) bs (start + 1) stop).size
⊢ (as.push bs[start])[i] = as[i]

case right
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
this✝ : start < bs.size
this : i < (foldl push (as.push bs[start]) bs (start + 1) stop).size
⊢ i < (as.push bs[start]).size
no goals