chore: add isSet

Simon he · Simon he · commit 0d2f295419b1 · 2022-06-23T15:57:42.000+08:00
diff --git a/src/isSet.ts b/src/isSet.ts
@@ -0,0 +1,4 @@
+import { _toString } from './common';
+export function isSet(o: any) {
+  return _toString.call(o) === '[object Set]';
+}
