title: lowercase first n characters
body: <p>I'm trying to lowercase the first n characters in a string.</p>
  
  <p>For example, say I want to lowercase the first 4 characters in this string:</p>
  
  <pre><code>String1 = 'HELPISNEEDED'
  </code></pre>
  
  <p>I would like the output to look like this:</p>
  
  <pre><code>String1 = 'helpISNEEDED'
  </code></pre>
  
  <p>I thought I could use this:</p>
  
  <pre><code>String1 = String1[4].lower() + String1[5:]
  </code></pre>
  
  <p>but this gives me this output:</p>
  
  <pre><code>String1 = 'iSNEEDED'
  </code></pre>
  
  <p>Any idea on how I'm doing this wrong?</p>