chore: add explaining comments

src/index.ts

@@ -3,6 +3,10 @@ import deepmerge from 'deepmerge'
 import { Shape, ThemeTokens } from './core/types'
 import { esModuleInterop } from './core/import-module'
 
+// For better DX, theme can be polymorphed, for example:
+// withTokens(() => ...),
+// withTokens(withTokens(() => ...), () => ...)
+// withTokens(withTokens(() => ...)(), () => ...)
 type ThemeFn<T> = ThemeFn1<T> | ThemeFn2<T>
 type ThemeFn1<T> = (primitives: T) => ThemeTokens
 type ThemeFn2<T> = (primitives: T) => ThemeFn1<T>
@@ -13,6 +17,7 @@ export function withTokens<T extends Shape<any>, U extends Shape<any> = Shape<an
 ) {
   return (primitives1?: T) => (primitives2?: U) => {
     const composedPrimitives = deepmerge(primitives1 || {}, primitives2 || {})
+    // Interop needed for using transpiled esm modules.
     const theme1 = esModuleInterop<ThemeFn1<any>>(themeFn1 as any)
     const theme2 = esModuleInterop<ThemeFn1<any>>(themeFn2 as any)
     if (theme2 === undefined) {