title: What is the difference between ImmutableJS Map() and fromJS()?
body: <pre><code>var a = {address: {postcode: 5085}}
  
  var b = Immutable.fromJS(a)
  var c = b.setIn(['address', 'suburb'], 'broadview').toJS(); // no error
  console.log(c); 
  
  var d = Immutable.Map(a);
  var e = d.setIn(['address', 'suburb'], 'broadview').toJS(); // error invalid keyPath(…)
  </code></pre>
  
  <p>Could someone explain the difference.</p>
  
  <p>Thanks, </p>