Every jam session finds its way to G eventually, and its ii–V–I — Am7, D7, Gmaj7 — is a bar-band literacy test. The line below applies the construction recipe with a neat twist the key provides for free: the resolution lands on the open G string itself.
Reading the line
Bar one rides the open A: root for free, then C and E fretted above it, then C again stepping up into D — the whole-step approach. Bar two’s D7 stacks D, F#, A and drops to a low F#, the leading tone waiting a half step under G. Notice the two F#s in this line doing different work: one is a chord tone announcing the dominant, the other is an arrival ramp. Bar three resolves onto G at the third fret of the E string and keeps moving through B and D, F# easing back home; the final bar climbs G, B, D and ends ringing on the open G — the one note on a bass that needs no fingers to sound triumphant.
Practicing it
This is the walk to memorize for real-world use: G is guitar country, and a bassist who can walk its ii–V–I owns every country turnaround and half the songbook. Drill the F#-to-G resolution until it sounds inevitable at any tempo, use the G major scale map to find alternative approach notes, and then finish the set with the walk in D, which lifts the whole cell up the neck.