src/main/java/org/organicdesign/fp/xform/Xform.java
@Override public Xform<A> dropWhile(Fn1<? super A,Boolean> predicate) {
        if (predicate == null) { throw new IllegalArgumentException("Can't dropWhile without a function."); }
        return new DropWhileDesc<>(this, predicate);
    }
@Override public Xform<A> dropWhile(Fn1<? super A,Boolean> predicate) {
        if (predicate == null) { throw new IllegalArgumentException("Can't dropWhile without a function."); }
        return new DropWhileDesc<>(this, predicate);
    }
The number of items to drop from the beginning of the output.