code: @Override
    public boolean visit(final NamedParameterNode<?> node) {
      this.graphStr
          .append("  ")
          .append(node.getName())
          .append(" [label=\"")
          .append(node.getSimpleArgName())           // parameter type, e.g. "Integer"
          .append("\\n")
          .append(node.getName())                    // short name, e.g. "NumberOfThreads"
          .append(" = ")
          .append(config.getNamedParameter(node))   // bound value, e.g. "16"
          .append("\\n(default = ")
          .append(instancesToString(node.getDefaultInstanceAsStrings())) // default value, e.g. "4"
          .append(")\", shape=oval];\n");
      return true;
    }
docs: Process current configuration node for the named parameter.
  
  @param node Current configuration node.
  @return true to proceed with the next node, false to cancel.