docs: def map_values(self, func):
          """
          :param func:
          :type func: T -> U
          :rtype: TDict[U]
  
          Usage:
  
              >>> TDict(k1=1, k2=2, k3=3).map_values(lambda x: x*2) == {
              ...     "k1": 2,
              ...     "k2": 4,
              ...     "k3": 6
              ... }
              True
          """
          return TDict({k: func(v) for k, v in self.items()})