title: Accessing a config variable on heroku returns a 500 error
body: <p>I have tested and set a config variable to heroku for my flask app using the following code: </p>
  
  <pre><code>api = os.environ.get['API_KEY']
  </code></pre>
  
  <p>Testing it on foreman seems to work, but returns a 500 internal server error when deployed on heroku. Would the error be caused by the code above?  </p>