'Adds a :class:`KeventDescriptor` to the collection for the given
path.
:param path:
The path for which a :class:`KeventDescriptor` object will be
added.
:param is_directory:
``True`` if the path refers to a directory; ``False`` otherwise.
:type is_directory:
``bool``'

def add(self, path, is_directory):

    with self._lock:
        path = absolute_path(path)
        if (not self._has_path(path)):
            self._add_descriptor(KeventDescriptor(path, is_directory))
