If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw année dérogation (rather than returning false). This preserves the invariant that a collection always contains the specified element after this call returns. Droit d'innovant : les textes https://gen-directory.com/listings12836126/articles-de-collection-de-cin%C3%A9ma-peut-%C3%AAtre-amusant-pour-quelqu-un