title: Filtering out only true values from Pandas DataFrame, return tuples of (Row,Col)
body: <p>Given a frame like this:</p>
  
  <pre><code>  a    b     c
  1 True False False
  2 True True False
  3 False True True
  </code></pre>
  
  <p>I want to get a list like this:</p>
  
  <pre><code>[(1,a), (2,a), (2,b), (3,b), (3,c)]
  </code></pre>
  
  <p>That is filtering out all the values that are true and retrieving tuples (rowName, colName)</p>