A = xa.bandwidth();
var nodeSizeB = xb.bandwidth();

var networkHeightA = nodeSizeA + nodeMargin * 2;
var networkHeightB = nodeSizeB + nodeMargin * 2;

var link = function(d) {
  // console.log(nodeSizeB, nodeSizeA, nodeMargin, d.bi, xb(d.bi))
  var p = "M" + (xb(d.bi) + nodeSizeB / 2) + "," + (nodeSizeB + nodeMargin)
      + "C" + (xb(d.bi) + nodeSizeB / 2) + "," + (nodeSizeB + networkMargin / 3 + nodeMargin)
      + " " + (xa(d.ai) + nodeSizeA / 2) + "," + (networkMargin - networkMargin / 3 + nodeMargin)
