src/main/java/org/organicdesign/fp/xform/Xform.java
public static <T> Xform<T> of(Iterable<? extends T> list) {
        if (list == null) { return empty(); }
        return new SourceProviderIterableDesc<>(list);
    }
public static <T> Xform<T> of(Iterable<? extends T> list) {
        if (list == null) { return empty(); }
        return new SourceProviderIterableDesc<>(list);
    }
Static factory methods