code: def add_keyed(self, value, key, date=None, return_value=False):
          
          return self.add(value, date, return_value, key)
docs: Add keyed metrics data to collection.
  
          Args:
              value (str): The value of the metric.
              key (str): The key value for keyed metrics.
              date (str, optional): The optional date of the metric.
              return_value (bool, default:False): Tell the API to return the updates metric value.
  
          Return:
              dict: If return_value is True a dict with the current value for the time period
                  is returned.