code: def map_keys_deep(f, dct):
      
      return _map_deep(lambda k, v: [f(k, v), v], dct)
docs: Implementation of map that recurses. This tests the same keys at every level of dict and in lists
      :param f: 2-ary function expecting a key and value and returns a modified key
      :param dct: Dict for deep processing
      :return: Modified dct with matching props mapped