Assigning function to prototype member results in Uncaught ReferenceError

Sat 2018.09.08

I am attempting to test a module function between var exports={}; statements.

http://www.espruino.com/Writing+Modules

function testLED(pin) {
  this.p = pin[0];
};

exports = testLED;


testLED.prototype.testUR = function() {
  var nInt = 42;
    console.log( "inside testUR() " + nInt );
};

exports.create = function() {
  return new testLED([A5]);
};

The IDE shows correct syntax check in right-hand editor pane.

On immediate send to device, Uncaught ReferenceError: "testUR" is not defined
despite the fact I just created the function definition. Observing the 'this' contents confirms this

1v99 (c) 2018 G.Williams
>Uncaught ReferenceError: "testUR" is not defined
 at line 1 col 11
exports = testUR;
          ^
=undefined
>this
={
  "E": function () { [native code] },
  "exports": {  },
  "testLED": function (pin) { ... },
  "ReferenceError": function () { [native code] },

Ideas anyone?