def project(self):
        """str: Default project to use for queries performed through IPython
        magics

        Note:
            The project does not need to be explicitly defined if you have an
            environment default project set. If you do not have a default
            project set in your environment, manually assign the project as
            demonstrated in the example below.

        Example:
            Manually setting the context project:

            >>> from google.cloud.bigquery import magics
            >>> magics.context.project = 'my-project'
        """
        if self._project is None:
            _, self._project = google.auth.default()
        return self._project