docs: def combine_ranked_stations(rankings):
      """ Combine :any:`pandas.DataFrame` s of candidate weather stations to form
      a hybrid ranking dataframe.
  
      Parameters
      ----------
      rankings : list of :any:`pandas.DataFrame`
          Dataframes of ranked weather station candidates and metadata.
          All ranking dataframes should have the same columns and must be
          sorted by rank.
  
      Returns
      -------
      ranked_filtered_candidates : :any:`pandas.DataFrame`
          Dataframe has a rank column and the same columns given in the source
          dataframes.
      """
  
      if len(rankings) == 0:
          raise ValueError("Requires at least one ranking.")
  
      combined_ranking = rankings[0]
      for ranking in rankings[1:]:
          filtered_ranking = ranking[~ranking.index.isin(combined_ranking.index)]
          combined_ranking = pd.concat([combined_ranking, filtered_ranking])
  
      combined_ranking["rank"] = range(1, 1 + len(combined_ranking))
      return combined_ranking