title: How to concatenate multiple columns into single column (with no prior knowledge on their number)?
body: <p>Let say I have the following dataframe:</p>
  
  <pre><code>agentName|original_dt|parsed_dt|   user|text|
  +----------+-----------+---------+-------+----+
  |qwertyuiop|          0|        0|16102.0|   0|
  </code></pre>
  
  <p>I wish to create a new dataframe with one more column that has the concatenation of all the elements of the row:</p>
  
  <pre><code>agentName|original_dt|parsed_dt|   user|text| newCol
  +----------+-----------+---------+-------+----+
  |qwertyuiop|          0|        0|16102.0|   0| [qwertyuiop, 0,0, 16102, 0]
  </code></pre>
  
  <p>Note: This is a just an example. The number of columns and names of them is not known. It is dynamic. </p>