title: AttributeError: Can't get attribute 'ShapesDataset' on <module '__main__' (built-in)> Mask R-CNN
body: <p>I am trying to train my model on Mac M1 Pro but I keep on getting this error</p>
  <pre><code>Epoch 1/2
  Traceback (most recent call last):
    File &quot;&lt;string&gt;&quot;, line 1, in &lt;module&gt;
    File &quot;/Users/pauladdai/opt/anaconda3/envs/TensorMask/lib/python3.8/multiprocessing/spawn.py&quot;, line 116, in spawn_main
      exitcode = _main(fd, parent_sentinel)
    File &quot;/Users/pauladdai/opt/anaconda3/envs/TensorMask/lib/python3.8/multiprocessing/spawn.py&quot;, line 126, in _main
      self = reduction.pickle.load(from_parent)
  AttributeError: Can't get attribute 'ShapesDataset' on &lt;module '__main__' (built-in)&gt;
  </code></pre>