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_ ." *).

Lemma sym_bequiv : forall (b1 b2 : bexp), bequiv b1 b2 -> bequiv b2 b1.