title: Same Python code returns different results for same input string
body: <p>Below code is supposed to return the most common letter in the TEXT string in the format:</p>
  
  <ul>
  <li>always lowercase</li>
  <li>ignoring punctuation and spaces</li>
  <li>in the case of words such as "One" - where there is no 2 letters the same - return the first letter in the alphabet</li>
  </ul>
  
  <p>Each time I run the code using the same string, e.g. "One" the result cycles through the letters...weirdly though, only from the third try (in this "One" example). </p>
  
  <pre><code>text=input('Insert String: ')
  def mwl(text):
      from string import punctuation
      from collections import Counter
      for l in punctuation:
          if l in text:
              text = text.replace(l,'')
      text = text.lower()
      text=''.join(text.split())
      text= sorted(text)
      collist=Counter(text).most_common(1)
      print(collist[0][0])
  mwl(text)   
  </code></pre>