code: public static <R> DoubleFunction<R> doubleFunction(CheckedDoubleFunction<R> function) {
          return Unchecked.doubleFunction(function, Unchecked.RETHROW_ALL);
      }
docs: Wrap a {@link CheckedDoubleFunction} in a {@link DoubleFunction}.
  <p>
  Example:
  <code><pre>
  DoubleStream.of(1.0, 2.0, 3.0).mapToObj(Unchecked.doubleFunction(d -> {
  if (d &lt; 0.0)
  throw new Exception("Only positive numbers allowed");
  
  return "" + d;
  });
  </pre></code>