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 opp_inject_Z : forall n : Z, inject_Z (-n) == - inject_Z n.