How to use the sherpa.utils.err.IOErr function in sherpa

raise IOErr('notascii', filename)

    names, args = read_file_data(filename, sep, comment, require_floats)

    if colkeys is None:
        kwargs = []
        if ncols != 1:
            _check_args(ncols, dstype)
        kwargs.extend(args[:ncols])
        return (names, kwargs, filename)

    kwargs = []
    colkeys = list(colkeys)

    if len(names) > len(args):
        raise IOErr('toomanycols')

    assert(len(names) <= len(args))

    for key in colkeys:
        if key not in names:
            raise IOErr('reqcol', key, numpy.asarray(names, numpy.string_))
        kwargs.append(args[names.index(key)])

    _check_args(len(kwargs), dstype)
    return (colkeys, kwargs, filename)

def _require_key(hdu, name, fix_type=False, dtype=SherpaFloat):
    key = _try_key(hdu, name, fix_type, dtype)
    if key is None:
        raise IOErr('nokeyword', hdu._file.name, name)
    return key

Throws an exception if there aren't any.
    """

    if blockname is None:
        for hdu in tbl:
            if isinstance(hdu, fits.BinTableHDU):
                return hdu

    else:
        blockname = str(blockname).strip().lower()
        for hdu in tbl:
            if hdu.name.lower() == blockname or \
                    isinstance(hdu, fits.BinTableHDU):
                return hdu

    raise IOErr('badext', filename)

def _require_tbl_col(crate, colname, cnames, make_copy=False,
                     fix_type=False, dtype=SherpaFloat):
    """
    checked for new crates
    """
    name = str(colname).strip()
    if not crate.column_exists(name):
        raise IOErr('reqcol', name, cnames)

    # data = pycrates.get_colvals(crate, name)
    col = crate.get_column(name)

    if make_copy:
        # Make a copy if a filename passed in
        data = numpy.array(col.values)
    else:
        # Use a reference if a crate passed in
        data = numpy.asarray(col.values)

    if fix_type:
        data = data.astype(dtype)

    return numpy.column_stack(data)

def _require_key(crate, name, key, dtype=str):
    """
    checked for new crates
    """
    key = _try_key(crate, key, dtype)
    if key is None:
        raise IOErr('nokeyword', crate.get_filename(), name)
    return key

#    pycrates.is_pha(rmfdataset) == 1):
        #    raise IOErr('badfile', arg, "RMFCrateDataset obj")

        if pycrates.is_rmf(rmfdataset) != 1:
            raise IOErr('badfile', arg, "RMFCrateDataset obj")

        filename = arg
        close_dataset = True

    elif pycrates.is_rmf(arg) == 1:
        rmfdataset = arg
        filename = arg.get_filename()
        make_copy = False

    else:
        raise IOErr('badfile', arg, "RMFCrateDataset obj")

    # Open the response matrix by extension name, and try using
    # some of the many, many ways people break the OGIP definition
    # of the extension name for the response matrix.
    rmf = _get_crate_by_blockname(rmfdataset, 'MATRIX')

    if rmf is None:
        rmf = _get_crate_by_blockname(rmfdataset, 'SPECRESP MATRIX')

    if rmf is None:
        rmf = _get_crate_by_blockname(rmfdataset, 'AXAF_RMF')

    if rmf is None:
        rmf = _get_crate_by_blockname(rmfdataset, 'RSP_MATRIX')

    if rmf is None:

def _pack_image(dataset):
    if not(isinstance(dataset, Data2D) or
           isinstance(dataset, DataIMG)):
        raise IOErr('notimage', dataset.name)
    data = {}

    header = {}
    if hasattr(dataset, 'header') and type(dataset.header) is dict:
        header = dataset.header.copy()

    data['pixels'] = numpy.asarray(dataset.get_img())
    data['sky'] = getattr(dataset, 'sky', None)
    data['eqpos'] = getattr(dataset, 'eqpos', None)

    return data, header

if rmf is None:
        rmf = _get_crate_by_blockname(rmfdataset, 'RSP_MATRIX')

    if rmf is None:
        try:
            rmf = rmfdataset.get_crate(2)
        except IndexError:
            rmf = None

    if rmf is None or rmf.get_colnames() is None:
        raise IOErr('filenotfound', arg)

    data = {}

    if not rmf.column_exists('ENERG_LO'):
        raise IOErr('reqcol', 'ENERG_LO', filename)

    if not rmf.column_exists('ENERG_HI'):
        raise IOErr('reqcol', 'ENERG_HI', filename)

    # FIXME: this will be a problem now that we have
    # to pass the name of the matrix column

    if not rmf.column_exists('MATRIX'):
        raise IOErr('reqcol', 'MATRIX', filename)

    if not rmf.column_exists('N_GRP'):
        raise IOErr('reqcol', 'N_GRP', filename)

    if not rmf.column_exists('F_CHAN'):
        raise IOErr('reqcol', 'F_CHAN', filename)

if ncols != 1:
            _check_args(ncols, dstype)
        kwargs.extend(args[:ncols])
        return (names, kwargs, filename)

    kwargs = []
    colkeys = list(colkeys)

    if len(names) > len(args):
        raise IOErr('toomanycols')

    assert(len(names) <= len(args))

    for key in colkeys:
        if key not in names:
            raise IOErr('reqcol', key, numpy.asarray(names, numpy.string_))
        kwargs.append(args[names.index(key)])

    _check_args(len(kwargs), dstype)
    return (colkeys, kwargs, filename)

def get_image_data(arg, make_copy=True, fix_type=True):
    """
    get_image_data ( filename [, make_copy=True, fix_type=True ])

    get_image_data ( IMAGECrate [, make_copy=True, fix_type=True ])
    """
    filename = ''
    close_dataset = False
    if type(arg) == str:
        img = open_crate(arg)

        if not isinstance(img, pycrates.IMAGECrate):
            # ??????????????????????????????????######## dtn
            close_crate_dataset(img.get_dataset())
            # ??????????????????????????????????######## dtn
            raise IOErr('badfile', arg, "IMAGECrate obj")

        filename = arg
        close_dataset = True

    elif isinstance(arg, pycrates.IMAGECrate):
        img = arg
        filename = arg.get_filename()
        make_copy = False

    else:
        raise IOErr('badfile', arg, "IMAGECrate obj")

    data = {}

    data['y'] = _require_image(img, make_copy, fix_type)