title: Pandas df.str.split() on first element only
body: <p>I have a column in a dataframe with chat conversations of which the general format in each cell is: </p>
  
  <p>'<em>name agent</em> <em>:</em> <em>conversation</em>'</p>
  
  <p>I would like to create a new column that contains only the <em>conversation</em> part.</p>
  
  <p>I did that using the following code:</p>
  
  <pre><code>filtered_transcript_text['msgText'].str.split(':', expand = True)
  </code></pre>
  
  <p>However, this function creates a split for each occurrence rather than only for the first one. Is there a way of using the <em>split</em> function for only the first occurence of an instance?</p>
  
  <p>I am aware that I could merge the other created columns, however this seems devious to me. </p>