'Registers a kevent descriptor for the given path.
:param path:
Path for which a kevent descriptor will be created.
:param is_directory:
``True`` if the path refers to a directory; ``False`` otherwise.
:type is_directory:
``bool``'

def _register_kevent(self, path, is_directory):

    try:
        self._descriptors.add(path, is_directory)
    except OSError as e:
        if (e.errno == errno.ENOENT):
            pass
        else:
            raise
