
[;1m  path_open(Path, Filename, Modes)[0m

  Searches the path [;;4mPath[0m (a list of directory names) until the
  file [;;4mFilename[0m is found. If [;;4mFilename[0m is an absolute filename, [;;4m[0m
  [;;4mPath[0m is ignored. Then opens the file in the mode determined by [;;4m[0m
  [;;4mModes[0m.

  Returns one of the following:

   • [;;4m{ok, IoDevice, FullName}[0m - The file is opened in the
     requested mode. [;;4mIoDevice[0m is a reference to the file and [;;4m[0m
     [;;4mFullName[0m is the full name of the file.

   • [;;4m{error, enoent}[0m - The file cannot be found in any of the
     directories in [;;4mPath[0m.

   • [;;4m{error, atom()}[0m - The file cannot be opened.
