title: Pandas Series of lists to one series
body: <p>I have a Pandas Series of lists of strings:</p>
  
  <pre><code>0                           [slim, waist, man]
  1                                [slim, waistline]
  2                                     [santa]
  </code></pre>
  
  <p>As you can see, the lists vary by length. I want an efficient way to collapse this into one series</p>
  
  <pre><code>0 slim
  1 waist
  2 man
  3 slim
  4 waistline
  5 santa
  </code></pre>
  
  <p>I know I can break up the lists using</p>
  
  <pre><code>series_name.split(' ')
  </code></pre>
  
  <p>But I am having a hard time putting those strings back into one list.</p>
  
  <p>Thanks!</p>