title: JSON python get value
body: <p>How can I get the price value with the <code>get()</code> function instead of using <code>[]</code>?</p>
  
  <p>As you can see <code>availableToBack</code> and <code>availableToLay</code> dictionaries can be empty at one point and I am trying to prevent an error when it happens and return <code>None</code>.</p>
  
  <pre><code>u'ex':
      {u'availableToBack':
          [
              {u'price': 1.02,
              u'size': 2.15}
          ],
      u'availableToLay': [],
      u'tradedVolume': []
      }
  </code></pre>
  
  <p>The way I get price is:</p>
  
  <pre><code>price = ['ex']['availableToBack'][0][price]
  </code></pre>
  
  <p>But in case of availableToLay it would give a key error. I know there is another way which would give None if value does not exist.</p>
  
  <pre><code>price = get('ex')...
  </code></pre>
  
  <p>Just can't figure out how construct this complex version of it. Can you hep?</p>