title: importing file in python through multiple directories
body: <p>I have a directory structure like this in python:</p>
  
  <pre><code>- __init__.py (1)
  - folder1
      - __init__.py (2)
      - folder2
          - __init__.py (3)
          - file.py
  </code></pre>
  
  <p>how can I expose file.py?</p>
  
  <p>currently in <code>__init__.py(2)</code> I have:</p>
  
  <pre><code>from folder2 import file
  </code></pre>
  
  <p>do I have to add in <code>__init__.py(1)</code></p>
  
  <pre><code>from folder1 import file
  </code></pre>
  
  <p>and do I have to add anything to <code>__init__.py(3)</code>?</p>