snocTel (Extend (unrebind -> (x , xs))) y = Extend (rebind x (snocTel xs y))
snocTel (Extend (unrebind -> (x , xs))) y = Extend (rebind x (snocTel xs y))
snocTel (Extend (unrebind -> (x , xs))) y = Extend (rebind x (snocTel xs y))