title: python find repeated substring in string
body: <p>I am looking for a function in Python where you give a string as input where a certain word has been repeated several times until a certain length has reached. </p>
  
  <p>The output would then be that word. The repeated word isn't necessary repeated in its whole and it is also possible that it hasn't been repeated at all.</p>
  
  <p>For example: </p>
  
  <pre><code>"pythonpythonp" =&gt; "python"
  
  "hellohello" =&gt; "hello"
  
  "appleapl" =&gt; "apple"
  
  "spoon" =&gt; "spoon"
  </code></pre>
  
  <p>Can someone give me some hints on how to write this kind of function?</p>