Definition CReal_abs (x : CReal) : CReal :=
{|
  seq := CReal_abs_seq x;
  scale := CReal_abs_scale x;
  cauchy := CReal_abs_cauchy x;
  bound := CReal_abs_bound x
|}.

Lemma CReal_abs_left : forall x : CReal, x <= 0 -> CReal_abs x == -x.