diff --git a/common.ts b/common.ts
new file mode 100644
index 0000000..afc7277
--- /dev/null
+++ b/common.ts
@@ -0,0 +1,8 @@
+export type Pretty<T> = {
+    [K in keyof T]: T[K];
+};
+export type Expand<T> = T extends object
+  ? T extends infer O
+    ? { [K in keyof O]: Expand<O[K]> }
+    : never
+  : T
\ No newline at end of file