Breadth-first output of the b-tree

breadth-first output of the b-tree

    def depth_first(self, root):
        Q = [root]
        elems = []
        
        while len(Q):        
            current = Q.pop(0)

            elems.append(current.data)

            if current.left is not None:
                Q.append(current.left)
            if current.right is not None:
                Q.append(current.right)
        
        print(*elems)