anchor.diff:  (*
    * Load a checked file into mcache
    *
  - * This is loading the parsing data and tc data as Unknown (unless checked file is invalid)
  - *
  - * See above for the two phases of loading the checked files
  + * This is loading the parsing data, and tc data as Unknown (unless checked file is invalid)
  + *
  + * See above for the two steps of loading the checked files
    *)
   let load_checked_file (fn:string) (checked_fn:string) :unit =
  -  if checked_fn |> BU.smap_try_find mcache |> is_some then ()
  +  if checked_fn |> BU.smap_try_find mcache |> is_some then ()  //already loaded
     else
       if not (BU.file_exists checked_fn)
       then let msg = BU.format1 "checked file %s does not exist" checked_fn in
  
positive.code:         Inl msg
        | Some (Invalid msg, _) -> Inl msg
        | Some (Valid (dig, _), _) -> Inr dig
        | Some (Unknown _, _) -> failwith "Impossible: unknown entry in the cache for a dependence"
      in
      match digest with
      | Inl msg -> Inl msg
  
negative.code:   | [] -> Inr (("source", source_hash)::interface_hash@out)
    | fn::deps ->
      let cache_fn = Dep.cache_file_name fn in
      (*
       * It is crucial to get the digest of fn from mcache, rather than computing it directly
       * See #1668
       *)
      let digest =
        match BU.smap_try_find mcache cache_fn with
        | None ->  //this should really be impossible
          let msg = BU.format2 "For dependency %n, cache file %s is not loaded" fn cache_fn in
  