code: function expandTabs(content, tabWidth) {
      var idx = 0;
  
      // while we're not at the end of the string:
      // - is the character at the current position a tab?
      // - yes, replace with spaces and move the current position forward
      // - no, jump to the character after the next newline
      while (idx > -1 && idx < content.length) {
        while (content[idx] === '\t') {
          content = content.substring(0, idx) + repeat(' ', tabWidth) + content.substring(idx+1);
          idx += tabWidth;
        }
        idx = content.indexOf('\n', idx);
  
        // if there are no `\n` characters, break
        if (idx === -1) { break; }
  
        idx += 1;
      }
  
      return content;
    }
docs: do the tab/space replacement