Goal:
  
  ============================
   (forall (A : Type) (R : ReflectEq A) (x y : A), true = (x == y) -> x = y)


DEBUG:Going to execute:
let H := fresh x in
           intro
           H
Level 2: Backtrace:

The first hypothesis in the goal is not an equality.
Level 2: Backtrace:

The first hypothesis in the goal is not an equality.
Level 2: Backtrace:

The first hypothesis in the goal is not an equality.
Level 2: Backtrace:

The first hypothesis in the goal is not an equality.