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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 id_token_jwt_grant(request, token_uri, assertion):
 """Implements the JWT Profile for OAuth 2.0 Authorization Grants, but requests an OpenID Connect ID Token instead of an access token. This is a variant on the standard JWT Profile that is currently unique to Google. This was added for the benefit of authenticating to services that require ID Tokens instead of access tokens or JWT bearer tokens. Args: request (google.auth.transport.Request):
 A callable used to make HTTP requests. token_uri (str):
 The OAuth 2.0 authorization server's token endpoint URI. assertion (str):
 JWT token signed by a service account. The token's payload must include a ``target_audience`` claim. Returns: Tuple[str, Optional[datetime], Mapping[str, str]]: The (encoded) Open ID Connect ID Token, expiration, and additional data returned by the endpoint. Raises: google.auth.exceptions.RefreshError: If the token endpoint returned an error. """

    body = {
        'assertion': assertion,
        'grant_type': _JWT_GRANT_TYPE,
    }

    response_data = _token_endpoint_request(request, token_uri, body)

    try:
        id_token = response_data['id_token']
    except KeyError as caught_exc:
        new_exc = exceptions.RefreshError(
            'No ID token in response.', response_data)
        six.raise_from(new_exc, caught_exc)

    payload = jwt.decode(id_token, verify=False)
    expiry = datetime.datetime.utcfromtimestamp(payload['exp'])

    return id_token, expiry, response_data