Function getDefaultPythonVersion

packages/python/src/version.ts:84–110

({
  isDev,
}: {
  isDev?: boolean;
})

 * or an unsupported version is requested.
 */
export function getDefaultPythonVersion({
  isDev,
}: {
  isDev?: boolean;
}): PythonVersion {
  if (isDev) {
    return getDevPythonVersion();
  }

  const defaultOption = allOptions.find(
    opt => versionsEqual(opt, DEFAULT_PYTHON_VERSION) && isInstalled(opt)
  );
  if (defaultOption) {
    return defaultOption;
  }

  // Fallback to the latest installed version if the default isn't available
  const selection = allOptions.find(isInstalled);
  if (!selection) {
    throw new NowBuildError({
      code: 'PYTHON_NOT_FOUND',
      link: 'https://vercel.link/python-version',
      message: `Unable to find any supported Python versions.`,
    });
  }
  return selection;
}

function versionsEqual(a: PythonVersion, b: PythonVersion): boolean {
  return a.major === b.major && a.minor === b.minor;