title: Why "rv" in Flask testing tutorial?
body: <p>I am reading <a href="http://flask.pocoo.org/docs/0.10/testing/#the-first-test" rel="noreferrer">Flask's tutorial about testing</a>. There's such code there:</p>
  
  <pre><code>rv = self.app.get('/')
  assert 'No entries here so far' in rv.data
  </code></pre>
  
  <p>My question is: why is there a variable called <code>rv</code>? What does this abbreviation mean?</p>
  
  <p>I've been looking for it in Flask source code for a while, and I found several variables called that way:</p>
  
  <pre><code>app_rv = app(environ, start_response)
  </code></pre>
  
  <p>and</p>
  
  <pre><code>rv = run_wsgi_app(self.application, environ, buffered=buffered)
  </code></pre>
  
  <p>But, as you can see, <code>rv</code> here is not even possibly related to <code>rv</code> as response object in testing.</p>
  
  <p>I've been able to find out that "r" stays probably for "response", but what does the "v" mean?</p>