title: Python 3: return longest item in lists of lists
body: <p>If i have this data:</p>
  
  <pre><code>a = [['a', 'b', 'b', 'v', 'd'], 
       ['d', 'f', 'g'], ['q', 'w', 'e', 'r', 't', 'y'], 
       ['x', '123', 'v', 'b'], ['g', 'h', 'i']]
  </code></pre>
  
  <p>I want to run a function (preferably single line) that will return <code>123</code> as is it has the <em>longest string length</em> in the list of lists.  How can I do this?</p>
  
  <p>The only thing I saw was finding the longest list in a list of lists, so this is a slightly different problem.</p>