function testSharedSet(mechanism, mechanismShared) {
  mechanism.set('first', 'one');
  assertEquals('one', mechanismShared.get('first'));
  assertEquals(1, mechanismShared.getCount());
  const iterator = mechanismShared[Symbol.iterator]();
  let it = iterator.next();
  assertFalse(it.done);
  assertEquals(mechanism.get(it.value), 'one');
  it = iterator.next();
  assertTrue(it.done);
  assertEquals(it.value, undefined);
}
@param {!IterableMechanism} mechanism
@param {!IterableMechanism} mechanismShared