title: How to use a format string with TRY_TO_TIMESTAMP
body: <p>I want to test if a string is a valid timestamp according to a defined date format string. </p>
  
  <p>I'm using <code>TO_TIMESTAMP</code> with a format string:</p>
  
  <pre><code>TO_TIMESTAMP(time_string,'DD/MON/YYYY:HH24:MI:SS TZHTZM')
  </code></pre>
  
  <p>however </p>
  
  <pre><code>TRY_TO_TIMESTAMP(time_string,'DD/MON/YYYY:HH24:MI:SS TZHTZM')
  </code></pre>
  
  <p>gives an error.</p>
  
  <p>How do I do this in snowflake?</p>