title: Parse .ini sections with python-decouple
body: <p><a href="https://github.com/henriquebastos/python-decouple" rel="nofollow noreferrer">Documentation</a> has a paradigm where the only section is called <strong><em>settings</em></strong>
  This seems to be the default namespace for <em>python-decouple</em> thus if you have:</p>
  
  <pre><code>[settings]
  DEBUG=True
  </code></pre>
  
  <p>you can parse the config with:</p>
  
  <pre><code>from decouple import config
  DEBUG = config('DEBUG', default=False, cast=bool)  # no section argument
  </code></pre>
  
  <p>But what if we have custom sections like:</p>
  
  <pre><code>[sectionA]
  DEBUG=True
  
  [sectionB]
  foo="bar"
  </code></pre>
  
  <p>?</p>
  
  <p>I know that one can easily use <em>ConfigParser</em> to parse custom sections, like so:</p>
  
  <pre><code>config_parser.get('sectionA', 'DEBUG')   # the corresponding call in ConfigParser
  </code></pre>
  
  <p>but I was wondering how it's done through <em>python-decouple</em> since it also supports <em>.ini</em> files</p>