title: Immutable.js Set contains duplicate values
body: <p>I'm facing an issue with Immutable.js' Set, which according to the docs can only contains unique values. 
  The code in this <a href="https://jsfiddle.net/sylvaingirard/8qv7u3yw/2/" rel="nofollow noreferrer">fiddle</a> will result in 2 duplicate entries in the set.</p>
  
  <p>Although this unit test passes, the issue is most likely user error.</p>
  
  <pre><code>it('should only have unique object values', () =&gt; {
    const set = Set&lt;any&gt;();
    const newSet = set.add({ form: 'form1', name: 'control1', value: 10 });
    const finalSet = set.add({ form: 'form1', name: 'control1', value: 10 });
    expect(finalSet.count()).toBe(1);
  });
  </code></pre>
  
  <p>Anyone able to explain this?</p>