title: ImportError: No module named 'app'
body: <p>I am working on a project with following tree structure:</p>
  
  <pre><code>Project
    app
      main.py
      svg_to_png.py
      __init__.py
      tests
         __init__.py
         unittests
            basic_test.py
            __init__.py
  </code></pre>
  
  <p>I am importing app functions to basic_tests by using </p>
  
  <pre><code>from app.main import *
  </code></pre>
  
  <p>when I execute the <code>basic_test.py</code>, it gives the following error:</p>
  
  <pre><code>ImportError: No module named 'app'
  </code></pre>
  
  <p>Also, while in the top directory of the project, when I type <code>python3 -m app.main</code>, the program executes for a while, then gives the same import error at the following line</p>
  
  <p><code>from app.svg_to_png import do_svg2png</code></p>