title: Python - working with dictionary with unique values
body: <p>I have several lists of tuples similar to (city_name, city_code) which I store in  dictionary for practical reasons so I can easily map city_name to city_code. 
  Obviously both city name and code are unique.</p>
  
  <p>It is easy to retrieve the code of the city based on its name but sometimes I would like to be able to do it another way around like getting the name of the city from the code for which I do linear search among dictionary items which is pretty clumsy.</p>
  
  <pre><code>for c in cities.items():
             if c[1] == code:
                  name = c[0]
                  break
  </code></pre>
  
  <p>Is there a a better way to do this? I am using python 2.7.8 and I would like to keep this simple without any additional modules.</p>