Sweet Module example is not working

http://www.sweetjs.org/doc/1.0/tutorial.html#_sweet_modules

I tried the example given at the above link and it is giving me below error

/usr/lib/node_modules/@sweet-js/cli/node_modules/resolve/lib/sync.js:42 throw err; ^

Error: Cannot find module './es2015-macros'

Updated the path in import statement to 'import { class } from './es2015-macros.js'; ' i.e. added .js in the module name. Re-run the example but getting below error this time

/usr/lib/node_modules/@sweet-js/cli/node_modules/sweet-core/dist/syntax.js:360 throw new Error('Scopeset ' + debugBase + ' has ambiguous subsets ' + debugAmbigousScopesets); ^

Error: Scopeset {outsideEdge_5} has ambiguous subsets {outsideEdge_5}, {outsideEdge_5} at Syntax.resolve (/usr/lib/node_modules/@sweet-js/cli/node_modules/sweet-core/dist/syntax.js:360:17)