Equivalent to dict.items().
        
        Usage::
        
            >>> for key, node in DictTree.kv(d):
            >>>     print(key, DictTree.getattr(node, "population"))  
            MD 200000
            VA 100000

def kv(d):
        """Equivalent to dict.items().
        
        Usage::
        
            >>> for key, node in DictTree.kv(d):
            >>>     print(key, DictTree.getattr(node, "population"))  
            MD 200000
            VA 100000
        """
        return ((key, value) for key, value in iteritems(d) if key != _meta)