Add Parametric Morphism : CReal_plus
    with signature CRealEq ==> CRealEq ==> CRealEq
      as CReal_plus_morph.#[global]
Instance CReal_plus_morph_T
  : CMorphisms.Proper
      (CMorphisms.respectful CRealEq (CMorphisms.respectful CRealEq CRealEq)) CReal_plus.

Lemma inject_Q_plus : forall q r : Q, inject_Q (q + r) == inject_Q q + inject_Q r.