code: def v_depth(d, depth):
          
          if depth == 0:
              yield d
          else:
              for node in DictTree.v(d):
                  for node1 in DictTree.v_depth(node, depth-1):
                      yield node1
docs: Iterate values on specific depth.
          depth has to be greater equal than 0.
          Usage reference see :meth:`DictTree.kv_depth()<DictTree.kv_depth>`