Building the scales tutor

All the rules for defining which notes to play for a given scale are added in a JSON file named scales.json within a folder named json. Let's take a look at the first few lines in the scales.json file:

{
 "Major": [ 0, 2, 4, 5, 7, 9, 11 ],
 "Minor": [ 0, 2, 3, 5, 7, 8, 10 ],
 "Harmonic minor": [ 0, 2, 3, 5, 7, 8, 11 ],
 "Melodic minor": [ 0, 2, 3, 5, 7, 9, 11 ],
 "Major blues": [ 0, 2, 3, 4, 7, 9 ],
 "Minor blues": [ 0, 3, 5, 6, 7, 10 ],
...
}

Recall that a scale is a set of notes played sequentially. The first note of the scale is called its root or key. So if you play a scale starting at say the note B, you are playing the scale in the key of B.

Let's take the fourth item in the key-value pairs. The key is named "Melodic minor" and its associated value is [ 0, 2, 3, 5, 7, 9, 11 ]. This means that, to play a melodic minor scale in the key of B, you will take B as the first item—that is represented by 0 in the values list. The next key is two semitones above B, the...