code: @NotNull
      public OptionalDouble findLast() {
          return reduce(new DoubleBinaryOperator() {
              @Override
              public double applyAsDouble(double left, double right) {
                  return right;
              }
          });
      }
docs: Returns the last element wrapped by {@code OptionalDouble} class.
  If stream is empty, returns {@code OptionalDouble.empty()}.
  
  <p>This is a short-circuiting terminal operation.
  
  @return an {@code OptionalDouble} with the last element
  or {@code OptionalDouble.empty()} if the stream is empty
  @since 1.1.8