 It became , then , a question of finding something that had a riff , a form that could be interpreted , simply , in a band format . In ' Crossroads ' there was a very definite riff . He [ Johnson ] was playing it full @-@ chorded with the slide as well . I just took it on a single string or two strings and embellished it . Out of all of the songs it was the easiest for me to see as a rock and roll vehicle . 
