I am trying to override the touch detector to disable the brush on touch enabled devices.
when setting up the brush, I get an error that touchable is not a function

			brush = d3.brushX()
				.touchable(()=>{ // <-- throws error
					return false;
				})
				.filter(()=>{
					return !d3.event.shiftKey;
				})
				.extent([[0, 0], [width, height]])
				.on("start", () => {
					console.log('brush started');
				})

looking at the sourcecode doesn't seem to correlate with the information provided in the Readme. Is this a relic of the past or will this be exposed in the future?