title: How to know the directory where the python script is called?
body: <p>Let's say that I have a python script a.py in /A/B/a.py, and it's in the PATH environment variable. The current working directory is /X/Y/, and it's the directory where I call the /A/B/a.py.</p>
  
  <ul>
  <li>In a.py, how to detect /X/Y/? I mean, how to know in which directory the python call is made? </li>
  </ul>