def _load_mtdata(gzfile):
    """
    Simple helper function that finds the test data in the directory tree
    and loads it using :func:`gzip.open` and :func:`numpy.loadtxt`.

    :param gzfile: Filename
    :type gzfile: str
    :returns: data
    :rtype: numpy.ndarray
    """
    path = os.path.join(os.path.dirname(__file__), 'tests', 'data', gzfile)
    return np.loadtxt(gzip.open(path))