title: Python range len vs enumerate
body: <p>I read from <a href="https://stackoverflow.com/questions/11990105/rangelenlist-or-enumeratelist">range(len(list)) or enumerate(list)?</a> that using <code>range(len(s))</code> is not very good way to write Python. How one can write for loops in alternative way if we do not need to loop <code>len(s)</code> times but for example <code>len(s)//3</code> times or <code>len(s)-5</code> times? Is it possible to convert those loops to use <code>enumerate</code>?</p>
  
  <p>For example, I had a project where I had a list of 3n elements 's[0], s[1],...,s[3n-1]' and I needed to print them in a nx3 table. I wrote the code something like</p>
  
  <pre><code>for i in range(len(s)//3):
      row = str(s[3*i]) + " " + str(s[3*i+1]) + " " + str(s[3*i+2])
      print(row)
  </code></pre>