def is_outlier_detector(estimator):
    """Return True if the given estimator is (probably) an outlier detector.

    Parameters
    ----------
    estimator : object
        Estimator object to test.

    Returns
    -------
    out : bool
        True if estimator is an outlier detector and False otherwise.
    """
    return getattr(estimator, '_estimator_type', None) == 'outlier_detector'
