Definition prog_c : com :=
  SKIP.Definition prog_g : com :=
  WHILE BTrue DO
    SKIP
  END.Definition equiv_classes : list (list com)
  (* REPLACE THIS LINE WITH ":= _your_definition_ ." *).

Theorem CWhile_congruence : forall b1 b1' c1 c1', bequiv b1 b1' -> cequiv c1 c1' -> cequiv (WHILE b1 DO c1 END) (WHILE b1' DO c1' END).