code: def unlink(self, node, hyperedge):
          
          self.node_links[node].remove(hyperedge)
          self.edge_links[hyperedge].remove(node)
          self.graph.del_edge(((node,'n'), (hyperedge,'h')))
docs: Unlink given node and hyperedge.
  
          @type  node: node
          @param node: Node.
  
          @type  hyperedge: hyperedge
          @param hyperedge: Hyperedge.