added todo

pollen-file-tools.rkt

@@ -130,7 +130,8 @@
   (any/c . -> . boolean?)
   (->boolean (or path? string? symbol?)))
 
-
+;; todo: tighten these input contracts
+;; so that, say, a source-path cannot be input for make-preproc-source-path
 (define/contract (make-preproc-source-path path)
   (path? . -> . path?)
   (add-ext path POLLEN_PREPROC_EXT))