title: Push element to an immutable List without reassigning variable
body: <p>How to avoid reassign of variables while iterating over an immutable List, to create another one. I have the code below, which is working fine,</p>
  
  <pre><code>function foobar(stateValue) {
  let propsValue = List();
  stateValue.forEach((categoryItem) =&gt; {
      categoryItem.get('coveragePayorIds', List()).forEach((
          coveragePayorId) =&gt; {
          const category = categoryItem.get('category');
          propsValue = propsValue.push({
          category,
          coverage_payor_id: coveragePayorId,
          });
      });
  });
  return propsValue;
  }
  </code></pre>
  
  <p>I'm trying to make the <code>propsValue</code> a const. How it can be achieved?</p>