_compileNodeVM() {
    if (this._compiledNodeVM) return this;

    this._compiledNodeVM = new vm.Script(
      '(function (exports, require, module, __filename, __dirname) { ' + this._prefix + this._code + this._suffix + '\n})',
      {
        filename: this.filename,
        displayErrors: false
      }
    );

    return this;
  }
Will compile the code for NodeVM and cache it

@return {VMScript}