diff --git a/server/src/functors/IO.ts b/server/src/functors/IO.ts
index 207bf72..ccc4dd6 100644
--- a/server/src/functors/IO.ts
+++ b/server/src/functors/IO.ts
@@ -1,5 +1,6 @@
 import { compose } from 'ramda'
 
+// https://mostly-adequate.gitbook.io/mostly-adequate-guide/appendix_b#io
 export class IO {
 	public unsafePerformIO: any