Return the cut-nodes of the given hypergraph.
    
    @type  hypergraph: hypergraph
    @param hypergraph: Hypergraph
    
    @rtype:  list
    @return: List of cut-nodes.

def _cut_hypernodes(hypergraph):
    """
    Return the cut-nodes of the given hypergraph.
    
    @type  hypergraph: hypergraph
    @param hypergraph: Hypergraph
    
    @rtype:  list
    @return: List of cut-nodes.
    """
    nodes_ = cut_nodes(hypergraph.graph)
    nodes = []
    
    for each in nodes_:
        if (each[1] == 'n'):
            nodes.append(each[0])
    
    return nodes