code: function init(g) {
      g.nodes().forEach(function(u) {
        var attrs = g.node(u);
        attrs.y = _rankSep * attrs.rank;
        if (attrs.width) {
          attrs.width = parseInt(attrs.width);
        } else {
          attrs.width = attrs.dummy ? _edgeWidth : _nodeWidth;
        }
      });
    }
docs: /*
  Initializes the graph by ensuring that each node has a numeric width. If
  no width was assigned to a node, we assign a default value. Dummy nodes
  are assigned the value edgeWidth.