code: async function copyAndTransform(file, ampRuntimeVersion) {
    const originalHtml = await readFile(file);
    const ampFile = file.substring(1, file.length)
        .replace('.html', '.amp.html');
    const allTransformationsFile = file.substring(1, file.length)
        .replace('.html', '.all.html');
    const validTransformationsFile = file.substring(1, file.length)
        .replace('.html', '.valid.html');
  
    // Transform into valid optimized AMP
    ampOptimizer.setConfig({
      validAmp: true,
      verbose: true,
    });
    const validOptimizedHtml = await ampOptimizer.transformHtml(originalHtml);
  
    // Run all optimizations including versioned AMP runtime URLs
    ampOptimizer.setConfig({
      validAmp: false,
      verbose: true,
    });
    // The transformer needs the path to the original AMP document
    // to correctly setup AMP to canonical linking
    const optimizedHtml = await ampOptimizer.transformHtml(originalHtml, {
      ampUrl: ampFile,
      ampRuntimeVersion: ampRuntimeVersion,
    });
    writeFile(allTransformationsFile, optimizedHtml);
    writeFile(validTransformationsFile, validOptimizedHtml);
    // We change the path of the original AMP file to match the new
    // amphtml link and make the canonical link point to the transformed version.
    writeFile(ampFile, originalHtml);
  }
docs: Copy original and transformed AMP file into the dist dir.