def load(filename):
    """Load a :class:`ClusterTree` or :class:`BlockClusterTree` from file

    :param filename: file to import
    :type filename: String
    :return: object
    :rtype: BlockClusterTree or ClusterTree

    .. note:: Depends on :mod:`pickle`
    """
    import pickle
    with open(filename, 'rb') as infile:
        obj = pickle.load(infile)
    return obj
