def error(message, level="error", exit_code=1, **kwargs):
    kwargs["fg"] = kwargs.get("fg", "red")
    click.secho(u"error: {}".format(message), **kwargs)
    sys.exit(exit_code)
def get_evolution_covariances(self):
        """!
        @return (list) Covariance matrix (or variance in case of one-dimensional data) of each cluster on each step of clustering.