def var_edge_iter(self, source, reverse=False):
        # Adapted from the networkx bfs_edges function
        if reverse and isinstance(self, nx.DiGraph):
            neighbors = self.predecessors_iter
        else:
            neighbors = self.neighbors_iter
        visited = set()
        queue = deque([(source, neighbors(source))])

        while queue:
            parent, children = queue[0]
            try:
                child = next(children)
                if (parent,child) not in visited:
                    visited.add((parent,child))
                    if reverse:
                        yield child, parent
                    else:
                        yield parent, child
                    if not is_basevar_node(self, child) and not is_comp_node(self, child):
                        queue.append((child, neighbors(child)))
            except StopIteration:
                queue.popleft()
Get the name of this DBRef's collection as unicode.
dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.main/src/openmdao/main/depgraph.py/DependencyGraph.var_edge_iter--crossover with--dataset/ETHPy150Open mongodb/mongo-python-driver/bson/dbref.py/DBRef.collection