title: Flutter check if variable is NaN
body: <p>I have <code>var number;</code> and it gets assigned by some calculations.</p>
  
  <p>If I do <code>print(number);</code> I get <code>NaN</code> as response;</p>
  
  <p>I expected that I would be able to do something like </p>
  
  <pre><code>if (number is NaN)
  </code></pre>
  
  <p>But I get NaN is not defined.
  How to check if variable is <code>NaN</code> in flutter?</p>