title: How do you switch python 2 and 3 quickly?
body: <p>I need to use both python 2 and python 3.</p>
  
  <p>The only way to change the default python used upon opening a .py file to is change the PATH environment variable. The steps are troublesome.</p>
  
  <p>Can I have some windows batch script which modify the PATH variable for me?</p>
  
  <p>Thanks.</p>