ImportError: cannot import name 'BCELossMasked'

I followed the instruction given at and

I can use the pre-trained models, but when I try to train a model following the exact steps of the latter link, I get an error of

python --config_path config.json | tee training.log
Traceback (most recent call last):
  File "", line 16, in <module>
    from TTS.layers.losses import L1LossMasked, MSELossMasked, BCELossMasked
ImportError: cannot import name 'BCELossMasked'

I’m on a Ubuntu 18.04 machine.