'Create the root and sub-directories in which loopback files will be
created.'

def _initialise_directories(self):

    self._unattached_directory = self._root_path.child(self._unattached_directory_name)
    try:
        self._unattached_directory.makedirs()
    except OSError:
        pass
    self._attached_directory = self._root_path.child(self._attached_directory_name)
    try:
        self._attached_directory.makedirs()
    except OSError:
        pass
