code: function className(g) {
      g
        .attr("id", function(d){
          return "d3plus_group_" + d.d3plus.id;
        })
        .attr("class", function(d){
          var c = vars.class.value ? " " + fetchValue(vars, d, vars.class.value) : "";
          return "d3plus_" + shape + c;
        });
    }
docs: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Sets the class name for a group ----------------------------------------------------------------------------