def get_furthest_clusters(cluster_distance_df, cluster):
    """Returns the ID of the two clusters furthest from the specified cluster.
    Parameters
    ----------
    cluster_distance_df : dataframe
        A dataframe containing the distances between
        each pair of clusters.
    cluster: integer
        An integer indicating the ID of the cluster for which
        the nearest clusters are being identified."""
    sorted_distances = cluster_distance_df[cluster].sort_values(ascending=False)
    two_nearest_clusters = sorted_distances[0:2].index.values.astype(int)
    return two_nearest_clusters