title: How to read python dictionary and tuples
body: <p>Can someone help me read this Python dictionary-tuples?
  I am new to python and I can't get much out of it</p>
  
  <pre><code>Grammar = {'AB':('S', 'B'), 'BB':'A', 'a':'A', 'b':'B'}
  </code></pre>
  
  <p>Note: 
  The grammar is the grammar of a Context Free Grammar. </p>