The altered scale is actually the seventh mode of the melodic minor scale, also called Super Locrian mode. As its name implies, it contains all possible alterations of the dominant seventh chord. It is widely used in jazz with this chord (whether be it altered or not) in a major or minor V-I beat. For a minor V-I, most of the alterations are found in the natural minor scale corresponding to the first degree, so these tensions naturally resolve. However, that is not the case in the V-I major where the tensions will be more dissonant.
You'll find below the 5 different positions/shapes of the G Altered bb7 Uke scale in Slack-key Tuning (gCEG), along with their ascending tab patterns.
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