title: Adding 1 to Value in Dictionary
body: <p>I have seen others ways of adding 1 to a value in a dictionary. 
  I simply keep getting an error when I try to add a value of 1 to a dictionary key value in python.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>arr = {('1', '20'): [0], ('15', '14'): [0]}
  </code></pre>
  
  <p>I want to add 1 to key ('1', '20'). </p>
  
  <p>Here is my code:</p>
  
  <pre><code>w = 1
  x = 20
  arr[(w, x)] += 1
  </code></pre>
  
  <p>I get the error code:</p>
  
  <pre><code>TypeError: 'int' object is not iterable
  </code></pre>
  
  <p>I simply do not know what I am doing wrong. Any suggestions are greatly appreciated.</p>