whole_func_string: function gen(node) {
    if (node && !generator[node.type]) {
      throw new Error(`${node.type} is not supported in NFA/DFA interpreter.`);
    }
  
    return node ? generator[node.type](node) : '';
  }
func_code_string: function gen(node) {
    if (node && !generator[node.type]) {
      throw new Error(`${node.type} is not supported in NFA/DFA interpreter.`);
    }
  
    return node ? generator[node.type](node) : '';
  }
func_documentation_string: Helper `gen` function calls node type handler.