code: function computeSlotSegPressures(seg) {
  	var forwardSegs = seg.forwardSegs;
  	var forwardPressure = 0;
  	var i, forwardSeg;
  
  	if (seg.forwardPressure === undefined) { // not already computed
  
  		for (i=0; i<forwardSegs.length; i++) {
  			forwardSeg = forwardSegs[i];
  
  			// figure out the child's maximum forward path
  			computeSlotSegPressures(forwardSeg);
  
  			// either use the existing maximum, or use the child's forward pressure
  			// plus one (for the forwardSeg itself)
  			forwardPressure = Math.max(
  				forwardPressure,
  				1 + forwardSeg.forwardPressure
  			);
  		}
  
  		seg.forwardPressure = forwardPressure;
  	}
  }
docs: Figure out which path forward (via seg.forwardSegs) results in the longest path until the furthest edge is reached. The number of segments in this path will be seg.forwardPressure