code: def forecast(self, horizon, xs=None):
      return [self.mean.get()] * horizon
  
file_path: river/river/time_series/test_evaluate.py
imports: from __future__ import annotations
  from river import datasets, metrics, stats, time_series
label_desc: Use image node_id 3 for calling the MeanForecaster obj's underlying member method code with example usage: obj.forecast(horizon, xs) and returns: unknown