title: Deploy sklearn model with custom transformer
body: <p>I have a sklearn pipeline that has been defined in the following way:</p>
  <pre><code>from tools.transformers import MyTransformer
  
  ...
  
  pipe = Pipeline([
      ('mytransformer', MyTransformer()),
      ('lm', LinearRegression())
  ])
  
  ...
  
  </code></pre>
  <p>The structure of my code is</p>
  <pre><code>src
  ├── __init__.py
  ├── train.py
  └── tools
      └── transformers.py
  
  </code></pre>
  <p>I have trained my model and my pipeline is saved in a <code>.joblib</code> file. Now I want to use my model in another project. However, I need to move not only the <code>.joblib</code> file, but the whole <code>tools/transformers.py</code> structure. I think this is kind of difficult to maintain and hard to understand.</p>
  <p>Is there an easier way to make the pipeline work without the need of moving the code around with the exact same structure?</p>