def rcumode2band(rcumode):
    """
    Map rcumode to band string as used in beamctl arguments

    Parameters
    ----------
    rcumode: int or str
        The RCU mode.
    Returns
    -------
    band: str
        The band name.
    """
    rcumode = str(rcumode)
    if rcumode == "3":
        band = "10_90"
    elif rcumode == "4":
        band = "30_90"
    elif rcumode == "5":
        band = "110_190"
    elif rcumode == "6":
        band = "170_230"
    elif rcumode == "7":
        band = "210_250"
    else:
        raise ValueError('Undefined rcumode %{}'.format(rcumode))
    return band