patterns can now be async

repl/package.json

@@ -1,6 +1,6 @@
 {
   "scripts": {
-    "start": "snowpack dev",
+    "start": "snowpack dev --polyfill-node",
     "build": "snowpack build && cp ./public/.nojekyll ../docs && npm run build-tutorial",
     "static": "npx serve ../docs",
     "test": "web-test-runner \"src/**/*.test.tsx\"",
@@ -12,6 +12,7 @@
   },
   "dependencies": {
     "@tonaljs/tonal": "^4.6.5",
+    "@tonejs/piano": "^0.2.1",
     "chord-voicings": "^0.0.1",
     "codemirror": "^5.65.1",
     "estraverse": "^5.3.0",