Unexpected identifier in composer-common/lib/cardstore/businessnetworkcardstore.js:54

yo hyperledger-composer:businessnetwork

/home/xuzheng/.nvm/versions/node/v6.6.0/lib/node_modules/generator-hyperledger-composer/node_modules/composer-common/lib/cardstore/businessnetworkcardstore.js:54

    async get(cardName) {

          ^^^

SyntaxError: Unexpected identifier

    at Object.exports.runInThisContext (vm.js:76:16)

    at Module._compile (module.js:528:28)

    at Object.Module._extensions..js (module.js:565:10)

    at Module.load (module.js:473:32)

    at tryModuleLoad (module.js:432:12)

    at Function.Module._load (module.js:424:3)

    at Module.require (module.js:483:17)

    at require (internal/module.js:20:19)

    at Object.<anonymous> (/home/xuzheng/.nvm/versions/node/v6.6.0/lib/node_modules/generator-hyperledger-composer/node_modules/composer-common/index.js:56:43)

    at Module._compile (module.js:556:32)