Printing a playlist

>>> from playlist import *
>>> from song import *
>>>
>>>
>>> s1 = Song("/home/kwebb/music/Nina Simone-I Put a Spell on You.mp3")
>>> s2 = Song("/home/kwebb/music/Johnny Cash-Hurt.mp3")
>>> s3 = Song("/home/kwebb/music/The Blind Boys of Alabama-Way Down in the Hole.mp3")
>>>
>>> p = Playlist()
>>> p.add_song(s1)
>>> p.add_song(s2)
>>> p.add_song(s3)
>>>
>>> print(p)
Playlist contents:
   1: I Put a Spell on You by Nina Simone
   2: Hurt by Johnny Cash
   3: Way Down in the Hole by The Blind Boys of Alabama
Total duration: 570.15 seconds