title: Your typical sheep counting regular expression in python question
body: <p>at night, after saying my prayers, i typically count sheep to help me fall asleep.
  i want a regular expression to help me with the correct count.
  i want the following strings to match</p>
  
  <pre><code>0
  1sheep
  2sheepsheep
  3sheepsheepsheep
  </code></pre>
  
  <p>and so on.</p>
  
  <p>what is the regular expression for this?</p>
  
  <p>something like <code>'(\d+)(sheep){\1}'</code> if <code>{\1}</code> would do what i want it to do</p>
  
  <p>what if i count my sheep in pairs (<code>1sheepsheep</code> and <code>2sheepsheepsheepsheep</code>), what would the regular expression be then?</p>