lazylinop.wip.dwt: name '_dwt_qmf_decimation' is not defined

from lazylinop.wip import signal as lls
import numpy as np
import pywt

x = np.random.randn(16)
x = x.reshape(4, 4)
lls.dwt(x.shape, hfilter=np.array(pywt.Wavelet('haar').dec_hi), lfilter=np.array(pywt.Wavelet('haar').dec_lo))

fails with NameError: name '_dwt_qmf_decimation' is not defined