title: AssertionError: col should be Column
body: <p>How to create a new column in PySpark and fill this column with the date of today?</p>
  
  <p>This is what I tried:</p>
  
  <pre><code>import datetime
  now = datetime.datetime.now()
  df = df.withColumn("date", str(now)[:10])
  </code></pre>
  
  <p>I get this error:</p>
  
  <blockquote>
    <p>AssertionError: col should be Column</p>
  </blockquote>