ES6 modules are implicitly in strict mode.
See the [spec](S(http://www.ecma-international.org/ecma-262/6.0/#sec-strict-mode-code)
10.2.1 Strict Mode Code
* Module code is always strict mode code.
ES6 modules are implicitly in strict mode.
See the [spec](S(http://www.ecma-international.org/ecma-262/6.0/#sec-strict-mode-code)
10.2.1 Strict Mode Code
* Module code is always strict mode code.