title: No module named flask.__main__ with global interpreter (OK with virtualenv)
body: <p>I know that using virtual environments is the best practice, but I just want to sort out the issue for myself. So here is the story.
  I have a Flask app, have set up a virtual environment, and I'm running everything on Windows. Which works great!
  However if I run the very same app with my global Python interpreter which is <strong>the same as my virtual one</strong> - i get this error:</p>
  
  <pre><code>D:\Development\stempal&gt;python -m flask run
  C:\Anaconda3\python.exe: No module named flask.__main__; 'flask' is a package and cannot be directly executed
  </code></pre>
  
  <p>Note that the very same command runs perfectly in the virtual environment:</p>
  
  <pre><code>(venv) D:\Development\stempal&gt;python -m flask run
   * Serving Flask app "flask_app"
   * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
  </code></pre>
  
  <p>What is the difference?</p>