This slow blues waltz is consisted by not a simplechord progress. (see
below.)
MB solo starts mainly under the typical blue note scale tasting wild 'Texas
tenor'.
Gradually, MB heaps up the sole with his favorite fast altissimo phrases.
On 17bar, a beautiful bent-up explodes : altissimo A->C (on Bb; B->D)
G(A) just beore A(B) is clearly heard, so I guess bending note is made
by the fingering of altisimo C(D).
Anyway, a cool phrase.