docs: function _main() {
    const srcIndexPath = join(DIST_DIR, 'index.html');
    const src404BodyPath = join(SRC_DIR, '404-body.html');
    const dst404PagePath = join(DIST_DIR, '404.html');
  
    const srcIndexContent = readFileSync(srcIndexPath, 'utf8');
    const src404BodyContent = readFileSync(src404BodyPath, 'utf8');
    const dst404PageContent = srcIndexContent.replace(/<body>[\s\S]+<\/body>/, src404BodyContent);
  
    if (dst404PageContent === srcIndexContent) {
      throw new Error(
          'Failed to generate \'404.html\'. ' +
          'The content of \'index.html\' does not match the expected pattern.');
    }
  
    writeFileSync(dst404PagePath, dst404PageContent);
  }