title: Absolute import doesn't work in Python 3.7
body: <p>I have a directory set up like this</p>
  
  <pre><code>Project
     |
     |folder1
     |  |folder2
     |  |  |Script_A.py
     |
     |folder3
     |  |Script_B.py
  </code></pre>
  
  <p>I am trying to access a class named <strong>ClassB</strong> residing in <strong>Script_B.py</strong> from <strong>Script_A.py</strong> in Python 3.7. I am trying to achieve this using absolute imports. Here is the content of Script_A.py:</p>
  
  <pre><code>from folder3.Script_B import ClassB
  </code></pre>
  
  <p>There seems to be something I am missing. I don't understand how <strong>Script_A</strong> is supposed to be aware of the existence of <strong>Script_B</strong> or even of the folder <strong>folder3</strong> or even of <strong>Project</strong>. What tells python to look for these folders?</p>
  
  <p>I have read <a href="https://www.python.org/dev/peps/pep-0328/" rel="nofollow noreferrer">PEP328</a> and this doesn't answer any of my questions.</p>