code: def merge_obs(self):
          
          for model_type in self.model_types:
              self.matched_forecasts[model_type] = {}
              for model_name in self.model_names[model_type]:
                  self.matched_forecasts[model_type][model_name] = pd.merge(self.forecasts[model_type][model_name],
                                                                            self.obs, right_on="Step_ID", how="left",
                                                                            left_index=True)
docs: Match forecasts and observations.