title: Can't parse date from concatenated string
body: <p>I am about to lose my mind with something so apparently simple. I want to parse a string into a datetime but it keeps returning null.</p>
  <p>If I do <code>todatetime(strcat(2020,&quot;-11-7&quot;))</code> it returns null.
  And if I do <code>todatetime(&quot;2020-11-7&quot;)</code> it works.
  I compared both strings and they are equal.</p>
  <p>This is the code that I am testing:</p>
  <pre><code>let dateStr = strcat(2020,&quot;-11-7&quot;);
  let dateStr2 = &quot;2020-11-7&quot;;
  print dateStr == dateStr2 // True
  print todatetime(dateStr) == todatetime(dateStr2) // False
  </code></pre>
  <p>Any idea why is this happening and how can I solve it?</p>