Today's new key signature has 3 flats - the Bb & Eb that you are used to, and now Ab as well. This is the key signature for Eb major and C minor as well as a number of modes. Here's Eb major to practice before you attempt the tunes -
The Keys of Canterbury
This old English tune only spans a fifth but it's focused around Ab so it's a good way of practising what is 'new' about this scale.
Speed this up to jig tempo.
Another klezmer classic.
Aim for 120bpm
A couple of buskers making free with Papirosen.
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Just a few bars to notate. You'll need to work out the time and key signatures and it doesn't start on '1'. Almost two bars in . . .
If you didn't get that right, work out why before you move on.