src/main/java/org/organicdesign/fp/StaticImports.java
@SafeVarargs
    public static <T> ImSet<T> set(T... items) {
        if ( (items == null) || (items.length < 1) ) { return PersistentHashSet.empty(); }
        return PersistentHashSet.of(Arrays.asList(items));
    }
@SafeVarargs
    public static <T> ImSet<T> set(T... items) {
        if ( (items == null) || (items.length < 1) ) { return PersistentHashSet.empty(); }
        return PersistentHashSet.of(Arrays.asList(items));
    }
Returns a new PersistentHashSet of the values.  This data definition method is one of the few
methods in this project that support varargs.  If the input contains duplicate elements, later
values overwrite earlier ones.