code: def create_time_series(self, label_values, func):
          
          if label_values is None:
              raise ValueError
          if any(lv is None for lv in label_values):
              raise ValueError
          if len(label_values) != self._len_label_keys:
              raise ValueError
          if func is None:
              raise ValueError
          return self._create_time_series(label_values, func)
docs: Create a derived measurement to trac `func`.
  
          :type label_values: list(:class:`LabelValue`)
          :param label_values: The measurement's label values.
  
          :type func: function
          :param func: The function to track.
  
          :rtype: :class:`DerivedGaugePoint`
          :return: A read-only measurement that tracks `func`.