title: ImportError for some but not all classes in package installed from TestPyPI
body: <p>I am trying to publish a package on PyPI. First, I <a href="https://test.pypi.org/project/neuralpp/" rel="nofollow noreferrer">uploaded it to TestPyPI</a> then installed it on a fresh Conda environment with</p>
  <pre><code>python3 -m pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ neuralpp
  </code></pre>
  <p>However I am unable to import some classes from the package. The minimal example below illustrates this:</p>
  <pre class="lang-python prettyprint-override"><code># main.py
  from neuralpp.inference.graphical_model.representation.table.pytorch_log_table import PyTorchLogTable
  
  from neuralpp.inference.graphical_model.representation.factor import PyTorchTableFactor
  </code></pre>
  <p>When I run <code>python main.py</code>, the first import (<code>PyTorchLogTable</code>) works, but not the second (<code>PyTorchTableFactor</code>). See the error message at the end of the question.</p>
  <p>I checked the package files (within the Conda environment) and the required files are present. This also works fine in the original project I uploaded.</p>
  <p>Because the error message mentions <code>__init__.py</code>, I've added <code>__all__ = ['PyTorchTableFactor']</code> to it, even though I know the use of <code>__all__</code> is not mandatory. However, this has not changed anything. Besides, the <code>__init__.py</code> for <code>PyTorchLogTable</code> is also empty and that is imported correctly, further confirming that this is not the issue.</p>
  <p>What is wrong here, and how can I fix it?</p>
  <p>Error message:</p>
  <pre><code>  File &quot;main.py&quot;, line 2, in &lt;module&gt;
      from neuralpp.inference.graphical_model.representation.factor import PyTorchTableFactor
  ImportError: cannot import name 'PyTorchTableFactor' from 'neuralpp.inference.graphical_model.representation.factor' (/Users/rodrigobraz/opt/anaconda3/envs/test/lib/python3.8/site-packages/neuralpp/inference/graphical_model/representation/factor/__init__.py)
  </code></pre>