How to export api defination in loopback?

I am using loopback with ES6 (ECMA Script 2015).

There is command available to export api is lb export-api-def.

When I run this command on ubuntu terminal it's is giving an error:

> import jwt from 'jsonwebtoken'; ^^^^^^
> 
> SyntaxError: Unexpected reserved word
>     at exports.runInThisContext (vm.js:53:16)
>     at Module._compile (module.js:413:25)
>     at Object.Module._extensions..js (module.js:452:10)
>     at Module.load (module.js:355:32)
>     at Function.Module._load (module.js:310:12)
>     at Module.require (module.js:365:17)
>     at require (module.js:384:17)
>     at /home/unify/robo-api/node_modules/loopback-boot/lib/executor.js:247:20
>     at Array.forEach (native)
>     at defineModels (/home/unify/robo-api/node_modules/loopback-boot/lib/executor.js:228:23)
>     at setupModels (/home/unify/robo-api/node_modules/loopback-boot/lib/executor.js:196:3)
>     at execute (/home/unify/robo-api/node_modules/loopback-boot/lib/executor.js:39:3)
>     at bootLoopBackApp (/home/unify/robo-api/node_modules/loopback-boot/index.js:154:3)
>     at Object.<anonymous> (/home/unify/robo-api/server/server.js:23:1)
>     at Module._compile (module.js:434:26)
>     at Object.Module._extensions..js (module.js:452:10)
>     at Module.load (module.js:355:32)
>     at Function.Module._load (module.js:310:12)
>     at Module.require (module.js:365:17)
>     at require (module.js:384:17)
>     at module.exports.yeoman.Base.extend.generate (/usr/local/lib/node_modules/loopback-cli/node_modules/generator-loopback/export-api-def/index.js:38:15)
>     at Object.<anonymous> (/usr/local/lib/node_modules/loopback-cli/node_modules/yeoman-generator/lib/base.js:431:23)

I am not able to figure it out, how to run this (lb export-api-def) command with npm run script.

via Shubham Batra