title: Create a dataframe using tuples
body: <p>I have three tuples :</p>
  
  <pre><code>x = (1,2,3)
  y = (4,5,6)
  z = (7,8,9)
  </code></pre>
  
  <p>I want to create a DataFrame which has a column containing the variable name of the set and another column with the values. </p>
  
  <p>Example output:</p>
  
  <pre><code>x 1
  x 2
  x 3
  y 4
  ...
  ..
  </code></pre>