code: function _edgeViz(edge) {
        var viz = {};
  
        // Color
        var color_el = _helpers.getFirstElementByTagNS(edge, 'viz', 'color');
  
        if (color_el) {
          var color = ['r', 'g', 'b', 'a'].map(function(c) {
            return color_el.getAttribute(c);
          });
  
          viz.color = _helpers.getRGB(color);
        }
  
        // Shape
        var shape_el = _helpers.getFirstElementByTagNS(edge, 'viz', 'shape');
        if (shape_el)
          viz.shape = shape_el.getAttribute('value');
  
        // Thickness
        var thick_el = _helpers.getFirstElementByTagNS(edge, 'viz', 'thickness');
        if (thick_el)
          viz.thickness = +thick_el.getAttribute('value');
  
        return viz;
      }
docs: Viz information from edges