code: def get_ids(df_or_dict, column_id):
      
      if isinstance(df_or_dict, pd.DataFrame):
          return set(df_or_dict[column_id])
      elif isinstance(df_or_dict, dict):
          return set.union(*[set(df[column_id]) for _, df in df_or_dict.items()])
      else:
          raise TypeError("df_or_dict should be of type dict or pandas.DataFrame")
docs: Aggregates all ids in column_id from the time series container `
  
      :param df_or_dict: a pandas DataFrame or a dictionary.
      :type df_or_dict: pandas.DataFrame or dict
      :param column_id: it must be present in the pandas DataFrame or in all DataFrames in the dictionary.
          It is not allowed to have NaN values in this column.
      :type column_id: basestring
  
      :return: as set with all existing ids in energy_ratio_by_chunks
      :rtype: Set
      :raise: ``TypeError`` if df_or_dict is not of type dict or pandas.DataFrame