    "A declaration which can be contained in a [[Package]] or in another [[NestableDeclaration]].

     Functions, values, classes, interfaces and aliases are such declarations."
    shared sealed interface NestableDeclaration of
                                            FunctionOrValueDeclaration |
                                            ClassOrInterfaceDeclaration |
                                            ConstructorDeclaration |
                                            SetterDeclaration |
                                            AliasDeclaration
            satisfies AnnotatedDeclaration & TypedDeclaration {

        "True if this declaration is annotated with [[actual|ceylon.language::actual]]."
        shared formal Boolean actual;

        "True if this declaration is annotated with [[formal|ceylon.language::formal]]."
        shared formal Boolean formal;

        "True if this declaration is annotated with [[default|ceylon.language::default]]."
        shared formal Boolean default;

        "True if this declaration is annotated with [[shared|ceylon.language::shared]]."
        shared formal Boolean shared;

        "This declaration's package container."
        shared formal Package containingPackage;

        "This declaration's module container."
        shared formal Module containingModule;

        "This declaration's immediate container, which can be either a [[NestableDeclaration]]
         or a [[Package]]."
        shared formal NestableDeclaration|Package container;

        "True if this declaration is a toplevel declaration."
        shared formal Boolean toplevel;
    }