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+/**
+ * part of Hachette
+ * Facilitate listening to events
+ *
+ * Copyright (C) 2021 Wojtek Kosior
+ * Redistribution terms are gathered in the `copyright' file.
+ */
+
+function make()
+{
+ return new Set();
+}
+
+function subscribe(observable, cb)
+{
+ observable.add(cb);
+}
+
+function unsubscribe(observable, cb)
+{
+ observable.delete(cb);
+}
+
+function broadcast(observable, event)
+{
+ for (const callback of observable)
+ callback(event);
+}
+
+const observables = {make, subscribe, unsubscribe, broadcast};
+
+/*
+ * EXPORTS_START
+ * EXPORT observables
+ * EXPORTS_END
+ */