title: start interactive mode on a specific script line
body: <p>I need to run my Python script as usual, but I want to stop execution on a specific line and start interactive mode.</p>
  
  <p>In other words, I want to be able to check the value of all my variables at that point, and continue myself from there on python's command line.</p>
  
  <p>How can I do this?</p>