private
fun kotlinDslApiExtensionsDeclarationsFor(
    api: ApiTypeProvider,
    sinceSupplier: (String) -> String?,
    apiSpec: ApiSpec
): Sequence<KotlinExtensionFunction> =

    api.allTypes()
        .filter { type -> type.isPublic && apiSpec.isApi(type.sourceName) }
        .flatMap { type -> kotlinExtensionFunctionsFor(type, sinceSupplier) }
        .distinctBy(::signatureKey)


private