#: Alexandru Popescu changed the world a bit at a time by saying on  8/20/2005 8:09 PM :#
> #: chris changed the world a bit at a time by saying on  8/20/2005 7:51 PM :#
>> 
> 
> I think you should write it:
> 
> class Song
> 	[....]
> 
> 	def to_s
> 		"Song: #{@name}--#{@artist} (#{@duration})"
> 	end
> end
> 
> class KaraokeSong
> 	[...]
> 	def to_s
> 		super + + " [#{@lyrics}]"
> 	end
> 
> end
> 
> [...]
> puts aSong.to_s
> 
> :alex |.::the_mindstorm::.|
> 
> 

definitely no double +, just one +. as it was already explained Song#to_s should return a string, 
while the initial Song#to_s is just printing one and returning nil.

:alex |.::the_mindstorm::.|