title: Change the value of imported variable in ES6
body: <p>I'm using ES6 modules and am importing a variable from <code>moduleA</code> into <code>moduleB</code>:</p>
  
  <pre><code>//moduleA.js
  let a = 5;
  let b;
  
  export { a, b };
  
  //moduleB.js
  import { a, b } from './moduleA'
  
  a = 6;
  b = 1;
  </code></pre>
  
  <p>But on change/assignment in <code>moduleB</code> I'm getting error such as:</p>
  
  <blockquote>
    <p>a = 6;</p>
    
    <p>ReferenceError: a is not defined</p>
  </blockquote>
  
  <p>On the other hand I can <code>console.log(a)</code> in <code>moduleB</code>.</p>
  
  <p>It seams it is not possible to assign to imported variables? Is this true or am I missing the way to do it? Why is this not possible?</p>