title: How to switch to python2 in a particular terminal window temporarily?
body: <p>I have a big third-party python2.7 application, a bunch of python scripts, which is added into <code>PATH</code> and it requires python2.7 instead of python 3.5 which I have by default.</p>
  
  <pre><code>$ python
  Python 3.5.1 (default, Mar  3 2016, 09:29:07) 
  [GCC 5.3.0] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; 
  
  
  $ python2
  Python 2.7.11 (default, Mar  3 2016, 11:00:04) 
  [GCC 5.3.0] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>I run that application as <code>$ some_app arg1 arg2</code>. How can make it use python2 as a temporary solution, preferably only in that single terminal window?</p>
  
  <p>I don't substitute a call of that application with "python". I call it like <code>$ some_app arg1 arg2</code>. I don't want to change the version of python permanently or modify the source code of the application.</p>