title: Python .get from a Nested Dictionary
body: <p>There are a number of none try/except ways to obtain a key or <code>None</code> from a Python dictionary, the problem is I can't seem to find an effective way of doing it for a Nested dictionary, i.e. where I need <code>my_dict['author']['email']</code> since chaining <code>.get()</code> twice will hit a Nonetype. 
  I thought of extending the dictionary <code>.get()</code> to be able to chain nested dicts i.e <code>.get(['author']['email'])</code> - but that would mean I'd have to re-initiate everything into the custom dictionary type (I think)?  </p>
  
  <p>The specific situation is I have two-schema's by which data is stored in Mongodb for a small transition, and I'm trying to find the optimal way to fetch the right information. (All the data before storage is verified to be one of two schemas). </p>
  
  <p>So for example on a non-nested item, stored differently in the schemas one might do: </p>
  
  <pre><code>#get database_info
  author_name = database_info['author'] if database_info.get('author') else database_info['author_name'] 
  </code></pre>
  
  <p>or </p>
  
  <pre><code>author_name = database_info['author'] if 'author' in database_info else database_info['author_name'] 
  </code></pre>
  
  <p>But for <code>database_info['author']['email']</code> (Where Author is a dictionary object containing other keys,values), one must do: </p>
  
  <pre><code>try: author_email = database_info['author']['email']
  except: database_info['contributor']['email_address']
  </code></pre>
  
  <p>Is there an optimal way to one line this? One way I've thought about attacking it is like this (for an arbitrary path of nested dictionaries): </p>
  
  <pre><code>author_email = database_info['author']['email'] if database_info.get('author', {}).get('email') else database_info['contributor']['email_address']
  </code></pre>