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

def get_ids(df_or_dict, column_id):
    """
    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
    """
    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")