g(stompa)
        >>> playlist.songs
        [stompa]
        """

        self.songs.append(song)
        
if __name__ == '__main__':
    import doctest
    doctest.testmod()
	</pre>
	<p>
        Notice that we <code>import song</code>, so that we can use class <code>Song</code> it in our new class.
		If we run the above module, we will get no output, which means that the <code>doctest</code> passed. Now, let us create a new
		method that returns the total duration of all the <code>Song</code