The Mendiani page now has a class recording of the arrangement that we used to play with Mamadou. It was played as an intermediate piece by the leader, each time with a different part of the group, the rest going on with the accompaniment and Dunduns uninterrupted. The roll in the beginning is where the leader interacts emotionally with the group, building up more energy, and the whole piece serves as an additional impulse to speed up the rhythm:

Below is a video showing the breakdown of the introduction to Djansa that we're preparing for the performance. All tones and slaps are played by myself (just for now), the group comes in with the bases at the right time :) Here we go: