This is a study of the riff often called the “Box Shuffle” by guitar and bass players. It can be played decending or like this version, ascending. The advantage of this is that it is highly recognizable to any band that is familiar with blues. This allows you to start the song off and signal the band in at the IV chord if your rhythm and playing are strong. Since this riff avoids using the “3rd” of the chord it tends to work perfectly with the blues scale. This song also does not have a turnaround on bar 12, which tends to be common with this type of riff.