title: Get key by value in dictionary
body: <p>I made a function which will look up ages in a <code>Dictionary</code> and show the matching name:</p>
  
  <pre><code>dictionary = {'george' : 16, 'amber' : 19}
  search_age = raw_input("Provide age")
  for age in dictionary.values():
      if age == search_age:
          name = dictionary[age]
          print name
  </code></pre>
  
  <p>I know how to compare and find the age I just don't know how to show the name of the person. Additionally, I am getting a <code>KeyError</code> because of line 5. I know it's not correct but I can't figure out how to make it search backwards.</p>