rw [Nat.le_sub_iff_add_le hstart]
α : Type u_1
as bs : Array α
start stop : Nat
hstart : start ≤ stop
hstop : stop ≤ bs.size
hne : ¬start = stop
hstart' : start < stop
⊢ 1 ≤ stop - start
α : Type u_1
as bs : Array α
start stop : Nat
hstart : start ≤ stop
hstop : stop ≤ bs.size
hne : ¬start = stop
hstart' : start < stop
⊢ 1 + start ≤ stop