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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def default(scopes=None, request=None):
 """Gets the default credentials for the current environment. `Application Default Credentials`_ provides an easy way to obtain credentials to call Google APIs for server-to-server or local applications. This function acquires credentials from the environment in the following order: 1. If the environment variable ``GOOGLE_APPLICATION_CREDENTIALS`` is set to the path of a valid service account JSON private key file, then it is loaded and returned. The project ID returned is the project ID defined in the service account file if available (some older files do not contain project ID information). 2. If the `Google Cloud SDK`_ is installed and has application default credentials set they are loaded and returned. To enable application default credentials with the Cloud SDK run:: gcloud auth application-default login If the Cloud SDK has an active project, the project ID is returned. The active project can be set using:: gcloud config set project 3. If the application is running in the `App Engine standard environment`_ then the credentials and project ID from the `App Identity Service`_ are used. 4. If the application is running in `Compute Engine`_ or the `App Engine flexible environment`_ then the credentials and project ID are obtained from the `Metadata Service`_. 5. If no credentials are found, :class:`~google.auth.exceptions.DefaultCredentialsError` will be raised. .. _Application Default Credentials: https://developers.google.com\ /identity/protocols/application-default-credentials .. _Google Cloud SDK: https://cloud.google.com/sdk .. _App Engine standard environment: https://cloud.google.com/appengine .. _App Identity Service: https://cloud.google.com/appengine/docs/python\ /appidentity/ .. _Compute Engine: https://cloud.google.com/compute .. _App Engine flexible environment: https://cloud.google.com\ /appengine/flexible .. _Metadata Service: https://cloud.google.com/compute/docs\ /storing-retrieving-metadata Example:: import google.auth credentials, project_id = google.auth.default() Args: scopes (Sequence[str]):
 The list of scopes for the credentials. If specified, the credentials will automatically be scoped if necessary. request (google.auth.transport.Request):
 An object used to make HTTP requests. This is used to detect whether the application is running on Compute Engine. If not specified, then it will use the standard library http client to make requests. Returns: Tuple[~google.auth.credentials.Credentials, Optional[str]]: the current environment's credentials and project ID. Project ID may be None, which indicates that the Project ID could not be ascertained from the environment. Raises: ~google.auth.exceptions.DefaultCredentialsError: If no credentials were found, or if the credentials found were invalid. """

    from google.auth.credentials import with_scopes_if_required

    explicit_project_id = os.environ.get(
        environment_vars.PROJECT,
        os.environ.get(environment_vars.LEGACY_PROJECT))

    checkers = (
        _get_explicit_environ_credentials,
        _get_gcloud_sdk_credentials,
        _get_gae_credentials,
        lambda: _get_gce_credentials(request))

    for checker in checkers:
        credentials, project_id = checker()
        if credentials is not None:
            credentials = with_scopes_if_required(credentials, scopes)
            effective_project_id = explicit_project_id or project_id
            if not effective_project_id:
                _LOGGER.warning(
                    'No project ID could be determined. Consider running '
                    '`gcloud config set project` or setting the %s '
                    'environment variable',
                    environment_vars.PROJECT)
            return credentials, effective_project_id

    raise exceptions.DefaultCredentialsError(_HELP_MESSAGE)