def copy_series_from_dataframe(input_df, index_name, column_name):
    """
    Take a multi-index DataFrame, and make a copy of the data
    corresponding to a given index and column.

    Parameters
    ----------
    input_df : pandas.DataFrame
        The DataFrame to extract the data from.
    index_name : str
        The index-value of the needed rows.
    column_name : str
        The column-name of the needed values.

    Returns
    -------
    pandas.Series
        Copy of the data corresponding to given index- and column-name.
    """
    subject_data = input_df.xs(index_name, level=0, axis=0)[column_name].copy()
    return subject_data