anchor.diff:  
   %%------------------------------------------------------------------------------
   %% @doc
  -%% Check that `Path` is an accessable path, e.g. a directory to a network
  -%% mounted file system, that might be blocked due to network problems.
  +%% Return true if calling `stat` on `Path` was successful.
   %%
  -%% If the `Path` is _safe_ execute the MFA in the calling process.
  +%% This function will not cause `file` or `filelib` operations to block, in case
  +%% the underlying `stat` operation blocks. This is in contrast to `file` and
  +%% `filelib` behaviour, where `filelib:is_regular/1` on a path that is in a
  +%% stale NFS mount will cause other `filelib:...` operations on totally
  +%% unrelated paths to block, too.
   %%
  -%% This function will not clog the file I/O of other `file` or `filelib`
  -%% operations in case the underlying `stat` operation blocks.
  +%% Also, subsequent invocations will immediately return `false` if a check
  +%% for `Path`, that was initiated by previous invocation, has not returned yet.
   %%
  -%% For example, if an NFS mount is located at "/mnt/nfs" and a file
  -%% "/mnt/nfs/user-provided/a76f7e62" is expected to be a regular file then
  -%% `safeio:is_regular("/mnt/nfs", "user-provided/a76f7e62")` will be a safe way
  -%% to determine if the file is a regular file and even if the NFS mount is
  -%% stale, this function returns after a short timeout.
  -%%
  -%% Also, subsequent calls to `check` will immediately return `false` if a check
  -%% for `Path`, that was initiated by previous invocation, has not returned yet.
  -%% This mechanism works by starting an internal server for each distinct `Path`.
  +%% This mechanism works by starting an internal server for each distinct `Path`,
  +%% see {@link info/1}.
   %%
   %% @end
   %% ------------------------------------------------------------------------------
  
positive.code: %% Check that `RootDirectory++"/"++RelPath` is a re file.
  %% Return `false` if filesystem errors or timeouts were encountered.
  %%
  %% In contrast to {@link filelib:is_regular/1} this function will not
  %% clog the file I/O of other `file` or `filelib` operations in case
  %% the underlying `stat` operation blocks.
  %%
  %% For example, if an NFS mount is located at "/mnt/nfs" and a file
  %% "/mnt/nfs/user-provided/a76f7e62" is expected to be a regular file
  %% then `safeio:is_regular("/mnt/nfs", "user-provided/a76f7e62")`
  %% will be a safe way to determine if the file is a regular file and
  %% even if the NFS mount is stale, this function returns after a short
  %% timeout.
  %%
  %% Also, subsequent calls to the `is regular` will immediately return
  %% `false` if a check for "/mnt/nfs", that was initiated by previous
  %% invokation, has not returned yet.
  %% This mechanism works by starting an internal server for each distinct
  %% `RootDirectory`.
  %% @end
  %%------------------------------------------------------------------------------
  -spec is_regular(file:filename(), file:filename(), timeout()) -> boolean().
  
negative.code: 
  %%------------------------------------------------------------------------------
  %% @doc
  %% Return true if calling `stat` on `Path` was successful.
  %% @see can_stat/2
  %% @end
  %% ------------------------------------------------------------------------------
  -spec can_stat(file:filename()) -> boolean().
  