title: Python I/O not creating new line
body: <p>I have the following code:</p>
  
  <pre><code>lines[usernum] = str(user) + "\n"         
  f = open('users.txt','w')
  userstr = str(lines)
  f.write(userstr) 
  </code></pre>
  
  <p>Effectively I am modifying the <code>lines</code> list at <code>usernum</code>, then writing it back to the original file <code>'users.txt'</code>. However, even adding the "\n", everything gets written to one line rather than an individual line for each line in <code>lines</code>. Why is this?</p>