Goal:
  
  b : Byte.byte
  xs : t
  b0 : Byte.byte
  ys : t
  IHxs : forall ys : t,
         eqb xs ys = match compare xs ys with
                     | Eq => true
                     | _ => false
                     end
  ============================
   (locked false = true)


DEBUG:Going to execute:
Ltac.assumption
DEBUG LTAC Evaluated term: not_locked_false_eq_true