title: How to fill true values of a dataframe with column names?
body: <p>I have a DataFrame with True and False values.</p>
  
  <pre>
         A      B      C      D
  0  False  True   True   False
  1  False  False  True   False
  2  True   True   False  False
  </pre>
  
  <p>I want to fill the true values with column names and false values with 0. How can I do that?</p>
  
  <p>i.e To get the result as </p>
  
  <pre>
     A  B  C  D
  0  0  B  C  0
  1  0  0  C  0
  2  A  B  0  0
  </pre>