next => exact Nat.lt_of_lt_of_le h le
case h_6
size size' : Nat
le : size ≤ size'
x✝ : Node
a✝¹ a✝ : Nat
h : a✝ < size
⊢ a✝ < size'

case h_7
size size' : Nat
le : size ≤ size'
x✝ : Node
a✝¹ : Data.Classes
a✝ : Nat
h : a✝ < size
⊢ a✝ < size'
case h_7
size size' : Nat
le : size ≤ size'
x✝ : Node
a✝¹ : Data.Classes
a✝ : Nat
h : a✝ < size
⊢ a✝ < size'