'Get the items in a playlist specified by ``uri``.
Returns a list of :class:`~mopidy.models.Ref` objects referring to the
playlist\'s items.
If a playlist with the given ``uri`` doesn\'t exist, it returns
:class:`None`.
:rtype: list of :class:`mopidy.models.Ref`, or :class:`None`
.. versionadded:: 1.0'

def get_items(self, uri):

    validation.check_uri(uri)
    uri_scheme = urllib.parse.urlparse(uri).scheme
    backend = self.backends.with_playlists.get(uri_scheme, None)
    if (not backend):
        return None
    with _backend_error_handling(backend):
        items = backend.playlists.get_items(uri).get()
        ((items is None) or validation.check_instances(items, Ref))
        return items
    return None
