docs: function prepareRevision(revision) {
    console.log(`🍳  Preparing ${revision}...`);
  
    if (revision === LOCAL) {
      return babelBuild(LOCAL_DIR());
    } else {
      if (!fs.existsSync(TEMP_DIR())) {
        fs.mkdirSync(TEMP_DIR());
      }
  
      const hash = hashForRevision(revision);
      const dir = TEMP_DIR(hash);
  
      if (!fs.existsSync(dir)) {
        fs.mkdirSync(dir);
        execSync(`git archive "${hash}" | tar -xC "${dir}"`);
        execSync('yarn install', { cwd: dir });
      }
      for (const file of findFiles(LOCAL_DIR('src'), '*/__tests__/*')) {
        const from = LOCAL_DIR('src', file);
        const to = path.join(dir, 'src', file);
        fs.copyFileSync(from, to);
      }
      execSync(
        `cp -R "${LOCAL_DIR()}/src/__fixtures__/" "${dir}/src/__fixtures__/"`
      );
  
      return babelBuild(dir);
    }
  }