title: pandas.apply function returns <built-in method
body: <p>I am trying to convert timestamps to string dates in a dataframe proceeding this way:</p>
  
  <pre><code>def ts_to_date(ts):
      return str(ts.date)
  
  display(table["event_date_and_time"].apply(ts_to_date))
  </code></pre>
  
  <p>The issue is that the resulting pandas serie is filled with <strong>built-in method date of Timestamp object at 0...</strong> and not with the converted timestamps. What do I do wrong ?</p>
  
  <p>Thank you in advance</p>