def get_sigma(database_file_name='<STR_LIT>', e_min=np.NaN, e_max=np.NaN, e_step=np.NaN, t_kelvin=None):
file_extension = os.path.splitext(database_file_name)[<NUM_LIT:1>]<EOL>if t_kelvin is None:<EOL><INDENT>if file_extension != '<STR_LIT>':<EOL><INDENT>raise IOError("<STR_LIT>")<EOL><DEDENT>else:<EOL><INDENT>_df = get_database_data(file_name=database_file_name)<EOL>_dict = get_interpolated_data(df=_df, e_min=e_min, e_max=e_max,<EOL>e_step=e_step)<EOL>return {'<STR_LIT>': _dict['<STR_LIT>'],<EOL>'<STR_LIT>': _dict['<STR_LIT>']}<EOL><DEDENT><DEDENT>else:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>
retrieve the Energy and sigma axis for the given isotope

    :param database_file_name: path/to/file with extension
    :type database_file_name: string
    :param e_min: left energy range in eV of new interpolated data
    :type e_min: float
    :param e_max: right energy range in eV of new interpolated data
    :type e_max: float
    :param e_step: energy step in eV for interpolation
    :type e_step: float
    :param t_kelvin: temperature in Kelvin
    :type t_kelvin: float

    :return: {'energy': np.array, 'sigma': np.array}
    :rtype: dict