def _moder_input(nin, nout, **kwargs):
    """
    Write moder input.

    Parameters
    ----------
    nin : `int`
        tape number for input file
    nout : `int`
        tape number for output file

    Returns
    -------
    `str`
        moder input text
    """
    text = ["moder"]
    text += [f"{nin:d} {nout:d} /"]
    return "\n".join(text) + "\n"