title: Pandas - Writing string values to a Dataframe
body: <p>I have strings stored in 2 variables. I am trying to have this added to an empty Dataframe.</p>
  
  <pre><code>variable1 = abc
  variable2 = def
  
  
  df = pd.DataFrame(columns=['action'])
  </code></pre>
  
  <p>I am not sure how to have these two variables added to Dataframe df in column labelled <code>action</code>.</p>
  
  <p>Expected output:</p>
  
  <pre><code>action
  abc
  def
  </code></pre>