This intro to 'Sweet Home Chicago' contains all of the classic Robert Johnson turnaround patterns. It moves between the I-IV-I-V chord changes in the two measure phrase and uses that classic shuffle rhythm. I love the chord voicing for the B7 chord too - the 5th in the bass really adds a lot of dirt to the chord. Check out Robert Johnsons 'Sweet Home Chicago' here: https://youtu.be/O8hqGu-leFc