One of my favorite gypsy jazz tunes! This one always sounds spirited to me. Bellville, I’m told, is/was the “red light” district in Paris.
E-Z improv: The A section is a mixture of D major and D minor/blues scales stuff. Start with trying just D major scale, then slide in the b3 (F), b5 (Ab) and b7 (C) as you see fit. The B section starts with G minor and the D major again. You will sound like you know what you are doing if you can hit some Bb’s during the G minor. The last 4 bars of the B section are “up for grabs!” Follow the changes if you can… but even if you can, you may just want to jam out on the D blues scale here, then release all the clashes when you hit the last A section but focusing on D major more. Have Fun!