title: Repeated values when trying to Insert a row using the .insert()
body: <p>I have a txt file I'm trying to make lists from. The txt file has 3 columns tab separated (index, word, tag).</p>
  
  <p>Example of the txt file:</p>
  
  <pre class="lang-none prettyprint-override"><code>1   i   PRP
  2   want    VBP
  3   to  TO
  4   go  VB
  </code></pre>
  
  <p>What I'm trying to do is add a beginning and end of sentence marker (<code>&lt;s&gt;</code> for beginning and <code>&lt;/s&gt;</code> for the end).</p>
  
  <p>My code is as follows:</p>
  
  <pre><code>trainfile=open("/Users/Desktop/training.txt").read().split('\n')
  from collections import Counter, defaultdict
  
  trainlines=[]
  
  for line in trainfile:
      trainlines.append(line)
  
  indexlist=[]
  wordlist=[]
  taglist=[]
  
  word_tag_counts = defaultdict(Counter)
  for line in trainlines:
      if not line.strip():
          continue
      index, word, tags = line.split()
      word_tag_counts[word.lower()][tags] += 1
      indexlist.append(index)
      if index == "1":
          indexlist.insert(0, '0')
          wordlist.insert(0, '&lt;s&gt;')
          taglist.insert(0, '&lt;s&gt;')
      else:
          indexlist.append(index)
          wordlist.append(word)
          taglist.append(tags)
          if word == '.':
              taglist.append('&lt;/s&gt;')
              wordlist.append('&lt;/s&gt;')
          else:
              continue
  </code></pre>
  
  <p>The issue I'm having is my results for the indexlist are:</p>
  
  <pre><code>['0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',...]
  </code></pre>
  
  <p>and wordlist and taglist are the same problem:</p>
  
  <pre><code>['&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;', '&lt;s&gt;',...]
  </code></pre>
  
  <p>Why is the inserted property the only thing thats showing up in my entire list?</p>
  
  <p>What I want for a final result is:</p>
  
  <pre><code>indexlist: [0, 1, 2, 3, 4, 5, 6, 0, 1, 2...]
  wordlist: [&lt;s&gt;, i, want, to, go, home, &lt;/s&gt;, &lt;s&gt;, ...]
  </code></pre>