def METHOD_NAME(
    self,
    account_id,  # type: str
    api_version="2019-02-28-preview",  # type: Optional[str]
    token_request_options=None,  # type: Optional["_models.TokenRequestOptions"]
    **kwargs  # type: Any
):
    # type: (...) -> "_models.StsTokenResponseMessage"
    """Gets an access token to be used with Mixed Reality services.
    Gets an access token to be used with Mixed Reality services.
    :param account_id: The Mixed Reality account identifier.
    :type account_id: str
    :param api_version: Api Version.
    :type api_version: str
    :param token_request_options: Parameter group.
    :type token_request_options: ~azure.mixedreality.authentication._generated.models.TokenRequestOptions
    :keyword callable cls: A custom type or function that will be passed the direct response
    :return: StsTokenResponseMessage, or the result of cls(response)
    :rtype: ~azure.mixedreality.authentication._generated.models.StsTokenResponseMessage
    :raises: ~azure.core.exceptions.HttpResponseError
    """
    cls = kwargs.pop('cls', None)  # type: ClsType["_models.StsTokenResponseMessage"]
    error_map = {
        401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
    }
    error_map.update(kwargs.pop('error_map', {}))
    _client_request_id = None
    if token_request_options is not None:
        _client_request_id = token_request_options.client_request_id
    accept = "application/json"
    # Construct URL
    url = self.METHOD_NAME.metadata['url']  # type: ignore
    path_format_arguments = {
        'accountId': self._serialize.url("account_id", account_id, 'str'),
    }
    url = self._client.format_url(url, **path_format_arguments)
    # Construct parameters
    query_parameters = {}  # type: Dict[str, Any]
    if api_version is not None:
        query_parameters['api-version'] = self._serialize.query("api_version", api_version, 'str')
    # Construct headers
    header_parameters = {}  # type: Dict[str, Any]
    if _client_request_id is not None:
        header_parameters['X-MRC-CV'] = self._serialize.header("client_request_id", _client_request_id, 'str')
    header_parameters['Accept'] = self._serialize.header("accept", accept, 'str')
    request = self._client.get(url, query_parameters, header_parameters)
    pipeline_response = self._client._pipeline.run(request, stream=False, **kwargs)
    response = pipeline_response.http_response
    if response.status_code not in [200]:
        map_error(status_code=response.status_code, response=response, error_map=error_map)
        raise HttpResponseError(response=response)
    response_headers = {}
    response_headers['MS-CV']=self._deserialize('str', response.headers.get('MS-CV'))
    deserialized = self._deserialize('StsTokenResponseMessage', pipeline_response)
    if cls:
        return cls(pipeline_response, deserialized, response_headers)
    return deserialized