title: Apply pandas to_datetime to all date columns
body: <p>I am attempting to convert some columns to_datetime that come through read_csv as objects. The column names so far always include the term DATE, _DT, or timestamp. I am not sure how to properly address the Series I want to convert if it is within the list.</p>
  
  <pre><code>date_col = [col for col in list(df) if re.search('DATE', col)]
  dt_col = [col for col in list(df) if re.search('_DT', col)]
  ts_col = [col for col in list(df) if re.search('TIMESTAMP', col)]
  dt_cols = date_col + dt_col + ts_col
  
  for col in list(df):
      if col in dt_cols:
          col = pd.to_datetime(col)
  </code></pre>
  
  <p>This fails for unknown string format which I understand to be caused by referencing a string from the list. I am not sure what I need to place inside of the pd.to_datetime to appropriately reference the Series in each iteration of the loop.</p>