title: How to read a txt. file, copy the content into a new file and replace certain content
body: <p>I have a <code>.txt</code> file online filled with text such as:</p>
  
  <pre><code>"Type": "Internal",
  "Category": 1,
  "Presentation": 3,
  ...
  </code></pre>
  
  <p>I want to use Apps Script to read out the content of that file and ultimately save it in a new file with modified content. Specifically, I need to remove the underscore of some content but keep the rest intact.</p>