title: Python import modules issue
body: <p>I recently was asked to deliver a python project as part of an interview process.
  I tested my project on Windows and MacOSX, with Pycharm, Spyder, jupyter notebook and command line and everything works fine.</p>
  
  <p>However, the reviewer was unable to make the project work on his side, because of module import issues according to him.</p>
  
  <p>My modules are organized like this:</p>
  
  <pre><code>my_project/
    my_module.py
    main_module.py
    my_package/
      __init__.py
      my_submodule_1.py
      my_submodule_2.py
  </code></pre>
  
  <p>my_submodule_1.py:</p>
  
  <pre><code>import my_module
  import my_submodule_2
  </code></pre>
  
  <p>I haven't added any path related to this project in PYTHONPATH.
  The project main function is located in <code>main_module.py</code>.
  The reviewer seem to have problems with the modules imported in <code>my_submodule_1.py.</code></p>
  
  <p>Could anyone shed some light on possible mistakes here and why it would work on my side and not on his?</p>