mark to-dos as done

scratchpad/scratchpad.c

@@ -56,7 +56,7 @@ struct box inverse_cdf(float cdf(float), float p)
 {
     // given a cdf: [-Inf, Inf] => [0,1]
     // returns x such that cdf(x) = p
-    // to do: add bounds, add error checking
+    // [x] to do: add bounds, add error checking
     // [x] maybe return a struct or smth.
 
     struct box result;